Squirrel Proof Bird Feeder Challenge




Introduction: Squirrel Proof Bird Feeder Challenge

About: Black sheep engineer, Chartered, and very silly. Currently living in the UK. I have been fortunate to have lived, studied and worked in Hong Kong, Norway and California. I believe physical models help people…

If you like Birds, and feeding them nuts in bird feeders - chances are you are not a fan of Squirrels, who will boldly rock up and gorge themselves on all the nuts - and seem to view the typical bird feeder with about as much trepidation as Arnold Schwarzenegger views a 'tight' jam jar lid - no problemo - in seconds they are in!

This Instructable will show you how you might make a more Squirrel-Resistant Bird Feeder ('Squirrel-Proof' being pretty tricky!), and to try to lay out a case as to why want to use this as an opportunity to teach Design & Technology students about the iterative design process at Schools....more on this later, but yes, I am serious.

For all the mischief of squirrels, and the bad press the Grey variety have right now, I personally still admire their acrobatic skill and cognitive power to get the nuts with the same dedication of Tom Cruise in Mission Impossible! This makes them a perfect 'pseudo-client' to interrogate student's designs without mercy, and like all good design adventures, this took me to some fun places with technology, such as 3D scanning a skull on my phone.

I hope you enjoy this project, and whether you doing this as a teacher, or just for your own amusement / satisfaction - please share your highs and lows here, in Comments. Thanks!

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1. The Fortress (how to build a truly squirrel proof bird feeder).

  • Pros: Impenetrable to squirrels.
  • Cons: Less bird friendly and expensive.

2. The Up-Cycler (how to build a pretty good feeder, from recycled/up-cycled materials.

  • Pros: Cheap. Simple to make. Pretty good all-rounder.
  • Cons: Likely to be 'figured out' or 'cracked' by Squirrels over time. Less aesthetically pleasing.

3. The Slip-Slider (how to make a slightly better version of the average bird feeder by making it hard to hold onto).

  • Pros: Simple Design. Familiar Setup. Not too costly.
  • Cons: Can be 'cracked' by a squirrel, but not that easy to gobble up nuts.

4. Anatomy & Technology

  • This is an exploration of how to really understand the anatomy of a Squirrel's Jaw/Skull, such to take inspiration as to how to stop it getting 'purchase' on the nuts as easily. I got into 3D scanning...


Props and thanks to Chris Notap for his support, and kind use of some of his designs.

Thanks also to Natural History Museum for their kind advice around all things Squirrel.


As mentioned, I started this project considering how Schools could teach this as part of the D&T curriculum. If you know anything about public schools, you'll know budgets are often tight, so I also wanted to show that this project could be done very cheaply using recycled materials, and basic tools. Where possible, I have used readily available items like coat hangers, tin cans, plastics bottles, and even recycling left out on 'Bin Day' collection. However, I can suggest a few things which might be worthwhile to invest in...

Essential Tools:

Glue Gun, Pliers, Hacksaw, Scissors, Hammer, Screwdriver, Bandsaw, Drill.

Suggested Materials:

Sheet Metal, Sheet Plastic, Metal Coat Hangers, Pipes, Wire, Mesh, Springs, Nuts & Bolts, Rivets, Silicone Mastic, Epoxy Glue, Super Glue, Hot Melt Glue, Tin Cans, Recycling Bin stuff, Thrift Store 'junk', etc.

Recommended Extras:

Soldering Iron - can be basic electronics iron, but for joining larger metal pieces, this 100W Iron is more effective. LINK.

Tin Snips - better than scissors, for cutting thing metal sheets, tin cans, etc. LINK.

Welding Rods - useful as they are pre-cut and solder well. (LINK).

3D Printer - I own a £1500 printer, and a £185 Ender 3. Truly, the later is fine for 99% of your needs at School. LINK.

Disclaimer/Safety: I have suggested using certain processes and chemicals which should be adapted to the competence of the teacher/class. Please conduct all risk assessments and inform students accordingly. Neither the Author or DATA can assume responsibility for following this guide.

Step 1: Smile, You're on PIR Camera!

Passive InfraRed Cameras are great for detecting movement, and then starting to record the action. I found this 1080p HD camera on Amazon for the remarkable price of £35! The installation was easy, and although it encourages you to buy the 'premium extras' of the Cloud storage, you do not need them and can simply use the 'free' SD method. I purchased a 128Gb micro SD Card for around £15, and I found this will likely last 1 month or intermittent recordings.

Although I was lucky enough to install this in my back garden, it seems plausible that a school could position this.

The software runs through an App, which the Teacher can use to review recordings. The quality is impressive for the price.

Data Protection / Safeguarding / Cameras:

As with any recording equipment and safeguarding, best to ask your IT supervisor at your school what are the best arrangements, as each school/country will likely differ, as will parent's opinions. One would hope this no more stressful than recording the Xmas / Pantomime Performance.

My only suggestion would be to perhaps point the camera into a corner of the playground / wildlife area so as not to unnecessarily record children (aside from using up a load of memory!). Good luck!

PS - If you want a Camera inside a Feeder or Birdbox, you may also like this WiFi Bird Box Cam project I did. LINK.

Step 2:

Step 3: Why Is Design & Technology Struggling As a Subject in Schools?

I was hired to create this Instructable project (and a few other projects like it) in response to the decline in students taking Design and Technology (D&T) at School. This is somewhat baffling as at its best D&T is a great foundation to Design, Engineering, Science - and other 'creative problem solving' professions. But it is fair to say that if the standard is not high enough, it can end up being maligned as a subject for only 'making boxes in a woodwork shop', and lacking the rigour of other subjects like Engineering and Science, whilst lacking the freedom and expression of Arts.

Despite D&T being one of the subjects which started the careers of 'rockstar creatives' like ex-Apple's Jony Ive, the subject is under threat, with numbers dropping. (DATA Report - for more info. LINK.)

In an article about Jony's background, his father, Mike saw to it that "D&T became part of the core curriculum and moved it from being a ‘low status’ subject to an ‘integrated course that mixed academic study with making things’." 

What is odd is that we find ourselves here again years later, with the subject at risk of being 'low status' - a perception which is not helped by the fact that the D&T Curriculum is heavily focussed on grading things which are easy to grade, rather than figuring out how to grade the learning of skills like observation, empathy and questioning.

D&T needs to represent the best of what anyone working in the industry knows is the 'best bit' - working on tough challenges, and taking the setbacks in your stride.

Step 4: How Will Designing Against Squirrels Help Make You a Better Designer?

Through discussions with teachers and students, a common problem was the 'Fear of Failure'. This was two-fold:

Firstly Teachers were anxious about not teaching what would give students good grades - and this has meant that projects are often either too subjective (e.g. make a Clock Display or a Lamp - ie it has no 'wrong' answer) and had no risk of it 'not working' - ie failing. Yet of course all Designers know failure is simply par for the course, and what gets you from V1.0 to V2.0 and so on.

Secondly, Students were understandably affected by this conservatism, and rightly so - as the Curriculum does not give a clear framework of 'failure' being integral to the design process. In short they played safe, making what would not 'go wrong'.

The reason the Squirrel was chosen was that it avoided the 'Teacher' being the 'primary judge' - the Birds and the Squirrel are the 'Judges' of the design. The teacher is then more free to be a Coach/Mentor, and help students power-through the setbacks and failures - hopefully with a giggle, as let's face it, it's hard to stay mad at a Squirrel for long, especially when they are busting into everyone's Feeders indiscriminately. May the best designs go forward...

History is littered with the Pasteur's, Curie's and Edison's many failures - before they saw triumph. We hope this project is a disarming and fun introduction to embracing the inevitable highs and lows of Design.

Step 5:

Step 6: Chris Notap's Feeder

This might seem like a contentious thing, but I'm 'copying' an idea from Chris Notap - who's Squirrel Proof Bird Feeder I found on YouTube after a quick google search. I feel this raises an important point about 'Originality' and 'Credit' - but more importantly - 'Iteration'...

When I was at school, you had to 'not copy someone else's idea': There was 'honour' in sweating away on something in isolation and it is true that making your brain 'struggle' is good for your creativity. However, with the internet in your pocket, any half intelligent kid will Google "Squirrel Proof Bird Feeder" as soon as you set the task. They are actually pretty dumb if they don't.

However, I would say there is an important difference between 'blindly copying', and 'copying to learn and improve on'. I took direct inspiration from Chris Notap's design, after evaluating countless designs online, but I wanted to learn two key things from building it:

  1. Chris's design used Glass. This is simply too dangerous for most school kids to use, and even quite risky to have in the garden with my 6 year old son...so I wanted to see if PolyCarbonate would work, but not get nibbled through (this is a genuine risk - Squirrels can bite through 1mm Aluminium if they wish).
  2. Chris's design, I call 'The Fortress' - because it is actually *so* good at keeping squirrels out, it also is pretty intimidating to Birds also. So although it is 10/10 on Squirrel Proofing, I can' t honestly say it's 10/10 on Bird Feeding (which is 50% of the Brief!), so this needs some redesign. When I contacted Chris, he said it did in fact take him about 2-3 weeks to get birds to go inside. I'm 4 weeks in, and still nothing, but they have started to show interest, so I think once we get a few 'ringleaders' in, we'll have a Bird Party in that Fortress!

My point is actually nothing new. In Renaissance times, apprentices were actually told to *copy* as a way to learn. I can assure you even the very act of trying to copy Chris's design has meant I learned a lot, but also made adjustments that suited my circumstances and sensibilities. I think these are all totally legitimate reasons to 'copy and learn', and should be validated as part of the D&T design process in the curriculum.

So my advice to students/teachers is to not pretend that there is not a wealth of tried and tested bird feeders out there, but that buying or building - and evaluating them helps you redesign your own better, with the benefit of that insight.

Another 'Squirrel obsessed' Engineer of note, is of Mark Rober, who has a 100m+ views video of his 'Ninja Assault Course'. This makes for amazing entertainment, and may well also inspire students in this project, but as his video shows, Squirrels are truly a worthy adversary, even for an Ex-NASA engineer! If you haven't guessed already, my point here is not to give kids a 'fool's errand', but rather to realise failure is not always a bad thing. Rober has made an entire second career based on creating V1.0 prototypes and telling people how much sweat and ingenuity it takes to get to V2.0 (check out Anti Theft Packaging). This IS real Design Process.

Indeed, one of the musings of this project, is 'why has Mark Rober / Chris Notap's work not been reappropriated into the D&T classrooms already?'. Having spoke to many teachers so far, there is a 'of course! why didn't I think of that!' reply I suspect is less about a teacher's creativity, and more about the curriculum being constraining to try something a little unorthodox. This write-up is also a provocation for feedback on why this might be so, and what might help in future - thanks for any comments, insights and suggestions below.

Thanks to Chris Notap, for being so generous with his time, and allowing me to share some of his work with you. Check out his awesome YouTube channel - here! Anyway - here's how I made Notap's Feeder, and some of my mods also...

Step 7: Full Marks for R&D / Offline Test Rigs

If any students wanted to know what great 'Offline R&D Rigs' looks like - this is tour de force: Chris needed to know what was the smallest size hole a squirrel was willing to squeeze into to get nuts. He could have googled the size of the skull, but that may have been too conservative, so he worked it out empirically, by creating an adjustable aperture - which prevented squirrels at 32mm diameter.

This became the Inner Diameter (ID) of his access holes, and for reference a Blue Tit is fine going in a 25mm hole, so 32mm is ample. I should note that Chris did not also test a combination of diameter and depth - and this might be a new area to explore, as of course 32mm is fine for some small birds, but does also restrict some larger birds too. I had a Birdbox also, so doubled checked this and it's all good.

I have also 'taken a risk' (in the name of Science!) and built mine our of Polycarbonate, to see if this is strong enough to keep squirrels out. If this lasts a year of interrogation with the local squirrels, I'd call this a 'pass'. I respect this is longer than a term, but I think this will be an interesting consideration for a teacher to 'build upon' the learnings from the previous academic year.

Step 8: Rings

As mentioned, I found this metal rail by the recycling bins on bin collection day on my street. It was exactly 32mm ID, but thinner walls than what Chris's copper pipe (which I had already annoyingly purchased). The thinner walls made for less work to cut on the bandsaw, and within an hour I had cut through all of these (about 18mm thick).

As you'd expect, there were metal burrs, and I sanded these off with a sanding sheet, and a rotary tool. Finally giving a polish on some Wet & Dry Paper, stuck to a sheet of MDF wood. You don't want any birds with cut of ruffled feathers, do you!?

Step 9: Pyramid of Rings

I really liked that Chris used Silicone to stick the rings together, and to the Glass (in my case Polycarbonate). I did actually have a go to see if I could solder them together, and although this works, it is simply much harder, and you'd still need to stick this to the polycarbonate/glass.

Also, having worked at Sugru (a silicone glue company) for 3 years, I happen to know a fair bit about adhesion, and it's a tricky thing to use a 'inflexible' glue (like Super Glue), when you join something like Metal to Glass/Plastic, which have very different expansion coefficients - meaning when it gets very hot or cold, the two materials will 'pop-off' the glue, as one will change size more than the other. Silicone, being flexible, accommodates for this. It's also cheap.

So, you rack them up like a Snooker, and they should form a nice pyramid. As you can see, I put some clingfilm (Saran Wrap) down to keep things from getting sticky. The white surface is also a bit of kitchen unit I got out of a skip...if you want to save money, the trick is to squirrel away finds when you come across them.

Step 10: Hinged Polycarbonate Sheets

Chris used an off-cut of Safety Belt to make his hinge (good squirrelling of found stuff), and I'd say this will work fine with Polycarbonate if you have this to hand. However, I opted to use a piano hinge, as I had some leftover from another project, and didn't have any Seat Belt scraps! I mention this to make the point that having students have to 'adapt' is not a bad exercise in lateral thinking... you could make a hinge out of many other things I'm sure, and I'd hope the D&T Curriculum starts to explore how a Teacher might somehow quantify 'Resourcefulness' as a skill as well as a virtue - given the state of our planet, we certainly need to reuse more than we recycle!

I cut the Hinge as shown with a Cut-Off Wheel. Then filed it smooth.

I used a circular saw to cut Two sides of the plastic sheet to the size of the 'upper' sides of the pyramid of rings, but would suggest school students use a bandsaw as it is safer. Note the slight 'overshoot', just like a house roof has extra beyond the walls of the house...something to see if students take note of(?).

With these pieces cut, I could make sure the Hinges fit in place.

Note - I did not YET cut the 'base' from the plastic...

Step 11: Wooden Base

In hindsight, I realised this step is easier if done before gluing the Polycarbonate in the next step.

I simply cut a pieces of 18mm wood off-cut I had to become the base. I then drilled some holes through both and bolted together. Lastly, I added some angle brackets (to fit a fence post).

Step 12: Glue Roof & Base

Note that the image shows the Bird House, 'on its side', so the 'base' is actually going to be the unhinged piece on the right side, and will be smaller slightly. (See last picture for final assembly).

I got all these set up just so before applying all the mastic to stick ONLY ONE SIDE of the roof down, but checking the other side folds nicely. I then used Masking Tape to secure it in place to dry overnight.

TIP: If the dimensions are a bit tricky - I suggest mocking it up in Cardboard first, so you are happy with how it all goes together. This is all good prototyping skills, and I often do things like this if I'm new to a material or process.

Step 13: Clips

I screwed the Fortress to the fence post.

I then added some 'clips' made from bent sections of Coat Hanger, but added two (as opposed to Chris's one) for extra security, in case the squirrels got smart!

Step 14: Feed Tray

I made a small tray out of the leftovers of Perspex. I realised that Chris has also thought about this nicely, and made it so a squirrel cannot poke it's nose through and get the nuts, so it is not at 'half' height of one of the rings, rather it is full height. A small detail, but a key one.

I glued this together with Epoxy. Safe to say, Teachers should supervise using any 'high performance / toxic / fast setting' glues, and ensure safe disposal of excess also.

Step 15: Finished!

All installed, with a few twigs (Chris's suggestion from his video), to encourage birds to perch and then go inside. Although some might consider this project a bit "#firstworldproblems" - I hope it is apparent, that this is about getting comfortable with failure, and getting going again after it - the project makes failure an 'essential ingredient', and actually by doing so levels the playing field that any urban, suburban or country school (in the UK at least) has squirrels not far away. As for whether this tackles 'big societal problem', my reply would be this is a 'primer', and the following two projects certainly 'ramp up' in this regard to solve less whimsical problems.

Project 2: https://www.instructables.com/DIY-Wind-Tunnel-3/

Project 3: https://www.instructables.com/Starting-Inclusive-Design-Projects/

Please also stay tuned, as we have more projects in the pipeline!

Step 16: Security Camera Gallery...

Surpassingly the Squirrel was not the first on the scene - it was some bees and a wood pigeon. But yes, "Charlie", our local squirrel got there within a day of it being installed, and I was impressed to say came to no harm, but also didn't get inside at all. At the time of writing, some 3 weeks later, still no breaking in. Chris's Fortress is still proving it's value - even with Polycarbonate sides.

Step 17:

Step 18: A Cheap, Make-shift Bird Feeder (From Water Bottle)

Somewhat in response to Chris's formidable Fortress, I wanted to make sure this challenge was possible with less resources, but still just as fun. I would even go as far as to say this might even be a good starting place in hindsight, as it certainly removes the 'fear' of 'wasting materials' or indeed, slaving away over a complex design, only to find a glaring error.

The credit goes to a maker "me13lake", here on Instructables, which naturally turned up when I Googled "Squirrel proof Bird Feeder + Recycled + Plastic Bottle"...If you can't be 'first', then the question is, can you be better?

I still had a great time making this, and enjoyed thinking it through as I was going...as you can see, I started with a large plastic bottle, which I cut the top third off.

Step 19: Seed Holder (From Tin Can)

I saw from the Feeder by "me13lake", that they used a small tin, which I didn't have. So I cut down a Baked Bean tin can to the shape.

However, as shown, I also played around with the idea of whether I could do away with the 'bolt', and bend a side wall of the Tin Can such that it would be self supporting. I suspect if I really got into it, I could create folds and ribs - to perfection, but I only had one Can, and it was getting tricky (and sharp!) so I decided to pass on this idea....again, all good exploration and experience!

Step 20: Stabilised Rotation (from Old PlayDoh Pot)

I realised that although my bottle was bigger, the wider mouth also made it more 'floppy', and it hung down on the seed tray, so I needed to stabilise the rotation, and create a smaller axis for it to rotate on.

I am quite pleased with this, as it uses no glue, and is just pressing a smaller plastic container into the other. I drilled a hole in both for the 6mm bolt/studding to pass through.

Note: It's hard to 'prescribe' this as a DIY step, as of course you may not happen to have this exact fit, but I think this underscores the point about School and indeed Households having 'Random Stuff Boxes' with odds and ends like this.

If you grew up in the 80's/90's as I did, you might remember Bitsa on TV (bootlegs now on YouTube!), and much of the great thing about this show was that it really used 'junk' well as a resource.

Step 21: Perch (from Coat Hanger)

Using Pliers or Shears, cut some lengths of Coat Hanger, such that you can form a 'Perch' as shown. This could be any way you think is best. I chose to bend mine such that it can be 'clamped' by the bolt and nut against the Tin Can.

I then Soldered the two ends as shown (Using a more heavy duty Soldering Iron, but a 'normal' soldering iron will work, it just needs longer to heat up. I do advise using Flux though!).

Step 22: Spinning Around!

With the assembly spinning nicely, I drilled a hole and put the bolt/studding into the fence post as shown. Filled with bird seed and ready to go!

Step 23: 1:0 to Me Vs Squirrel

It's early days yet, but on first week, Charlie the Squirrel has only looked flummoxed by the unstable rotation of the bottle, and had not bothered to try to get the nuts. Could be the bird feed though - might be less appealing? Either way, works nicely.

Step 24:

Step 25: Inspiration & Iteration

Once again, the mighty Instructables has done well, and I saw this invention on many "Squirrel Proof" blogs, and it was praised for it's simplicity and elegant solution of using a cable tie as a perch: Which is just sturdy enough to support a small bird, but bends if a larger bird or squirrel stands on it, and is too slippery to hold onto. Genius - "billr" - LINK.

However, I had seen squirrels on some other videos eventually pluck up the courage to 'hug' onto such pipes, as they have really sharp nails, and can dig into the plastic just enough. It's also not a very aesthetically pleasing form, but this is of course a bit nit picking, but I nonetheless wanted to see if I could build upon this...

Step 26: Upgrade the Grill

I wondered if I could make the feeder 'holes' stronger, so squirrels couldn't bend the thin mesh wire. I went from the typical '0.25mm mesh wire' to using welding rods of 1.6mm thickness - stiff enough not to be bent by a squirrel's jaw!

I used the Solder Gun to make a little 'fence', and then bent that into shape in a cylinder. This was then fitted to go inside a plastic tube I purchased. (LINK). I also created a central support, which I figured would come in handy later (and it did). Lastly, I cut some holes to allow any water to drain from the base.

The Tube is available in many different sizes, and this in itself would be a good experiment. Yet as you can see from the final image (spoiler), Squirrels are also pretty good at hanging by their back feet, upside-down, and ideally this Tube should be longer than 40cm (ie longer than the Squirrel's reach)....I'm sure you can see this will be my V2.0!!

Step 27: Biscuit Tin Soldering

Although you can of course buy some brushed steel, I have noticed that metal in Biscuit Tins is especially nice to work with - it cuts easily, and Solders well. When you consider a Biscuit Tin costs about £6, and a similar sheet of metal on Amazon/eBay - with shipping - costs about the same, and is NOT accompanied by Biscuits, although slightly wasteful, it's almost justifiable....

So I used some of this sweet smelling metal, and got to work making a Rain Cover / Hat for my Feeder Tube. I used a bulldog clip to show that even basic stationary like this works fine, even if I do have (somewhere) some welding camps, which of course do work best of all. My point is that you don't need a fancy workshop to tinker.

You might wish to prototype this in Cardboard first to get the dimensions all right, but I just jumped in.

Step 28: Spring Loaded Hat

I also drilled a hole in the top which would allow a hook to pass, and to 'spring load' the Hat to keep the squirrel out. It's a little hard to see from the pictures, but essentially I'm hooking the lower part internally, and then using this to secure the Hat.

Step 29: Gallery

So far so good. However, I found that although the squirrel did manage to get some of the nuts, the opening was so slight that it only got a little. I would not call this Squirrel 'Proof', but perhaps it's fair to say it slowed them down considerably. That said, you can see from the Camera Footage, that work still has to be done!

Step 30: Oh No!!!

As promised - bested by Charlie the Squirrel.

Indeed, this what drove Part 4...to try to optimise what I felt was a promising design...

> Make Longer than Squirrel's outstretched body and/or lengthen the hanging wire.

> Reduce Grill Size.

> Explore a 'Double Grill' - that Birds can peck, but squirrels cannot bite/nibble.

Hmmm....this is going to be a battle of minds. Charlie 1:0. Dang it!

...but wait, I have a cunning plan...scroll on...

Step 31: Camera Footage

Step 32:

Step 33: The Side Nibble

I watched the images and videos of Charlie the Squirrel making albeit slower work of the feeder than before, but still making progress. Her trick was to turn her head such that she could angle her teeth with the grill, and although she couldn't 'pluck' out a whole nut, she could 'chip' them so they fell out in small bits. Very slow and painstaking work, but there you go. Squirrel's have grit and dedication...gotta admire it!

I googled a few images of what their teeth were like, and it's safe to say they were formidable. I realised I needed a specimen, and found a nice one on eBay. I also checked with the Natural History Museum, that this was not illegal, and apparently as Squirrels are not a protected species, this is not prohibited, but one should by only from responsibly sourced and humane sellers. That said, this is a long list of checks, and as I found there was no free CAD files of 3D scans, I decided to make mine available open source, so you can just print it for free!

The following is the process to getting that result, but if you're in a hurry, you can just download and print the files!

Step 34: Specimen Mounting

I realised I actually had been sent two different jawbones, which didn't match, but no matter, I figured as this was a digital file, I'd mirror them anyway, and even the Skull worked better if one side was mirrored.

To begin I stuck each bone to a wooden stick on a bottle top (no expense spared!), with some Hot Melt.

If you are doing this, do wear gloves, as sometimes chemical residue might be present, or conversely any bacterial/slime which said chemicals didn't dissolve!

Step 35: 3D Scanning on My Phone (Photogrammetry)

I fist tried an App called Qlone, but long story short, the free version was not great, and left more of a 'blob' than a detailed scan.

I then looked at a more advanced App called KIRI Engine, which takes the images and processes these in the Cloud, using Machine Learning to 'stitch' the images together into a 3D object. The process is called 'Photogrammetry', and is a great rabbit hole to dive into if you want your Students to explore how this technology works, and I'm certain it'll be useful in future projects!

I recommend using a turntable, and a chequered mat from QLone to help orientate the scan and avoid 'exploding' as the second image on the following step shows. Sometimes the best of both worlds gives the best results!

Step 36: Output

The Output Files are in .OBJ format, and these were then taken into Fusion 360 to 'clean up', as well as to simplify the mesh. As you can see from the photo, the detail is amazing for something on a phone.

As mentioned, you may want to 'view' the file in the App first to see the image has not 'exploded' and is all one piece. If this is happening, use the mat as suggested, but also dust with Talc or Cornflour (or even spray with Hairspray) to make the surface Matte finish, and this reduces reflections which 'confuse' the AI.

Step 37: Print

I suggest printing in the orientations shown, with Support Material. I used PLA, on an Ender 3, with a 0.3mm Nozzle, at 'fine' detail, and it took about 4hours to print both. Slow, but worth it!

I put a pin in the side (drilled a hole first and inserted a length of paper clip), to make a 'hinge', not because I wanted to make it 'talk', but so I could understand the bite articulation of the jaw....mostly.

Step 38: Downloadable Squirrel Skull

Even though there is nothing illegal about buying skull specimens, I am rather pleased that this is a good scan that anyone can download, and it honestly seems good use of a printer to duplicate these Skulls for teaching, as truthfully, the bones are brittle and will likely be damaged over time, and certainly don't 'hinge' easily.

The next step is of course to use this to evaluate some prototypes that restrict nibbling of Squirrels - but still allow packing of Birds! A fine balance indeed!

Step 39:

Step 40: Squirrel Metrics & Ergonomics

In case you thought all this squirrel scanning was just for fun and games - think again, I now have a 'dummy squirrel' to evaluate how the bite/gnaw characteristics are happening as Charlie the Squirrel gets the nuts through my V1.0 'Slip Slider' concept...I can now 'mimic' what I observed on the security camera footage, and see how the squirrel can get good purchase on the nuts and nibble away. It's create when the theoretical model (in this case a 3D print) correlates with the observations from the 'field'.

It had occurred to me, that I could even scale the 3D print by say 20% to be a 'Young Squirrel' which might pose some insights if I get juvenile squirrels making this harder for me!

Step 41: Diagram of the Bite

As you can see from this scale drawing, this is the bite in effect. But...we might have an idea...

Step 42: A Possible Solution?

So now that I was able to really 'role play' being a squirrel (one of many reasons I love my 'job'), I realised that the bars were certainly working, as they forced the squirrel to have to tilt it's head to get purchase on the nuts. I figured if I can perhaps create a 'double ring' to keep the nuts away from the bite 'arc', but allow birds to 'peck' this might be a good way to proceed.

Step 43: Cheap Cheepers

Unlike Squirrel Skulls - which are generally permitted to buy online, one cannot do the same with Birds. Good news is, Skullsite is an amazing database and had Blue Tits and Great Tits - which are pretty small birds to see if these can peck out the nuts.

I scaled these, printed them out, and hoped this was a fair enough proxy (of course hard to say with feathers, etc.).

I cannot deny the urge to do small bird voices, but I remained professional, and focussed on the task at hand.

Anyway, I had to take a bit of a 'guesstimate' on the interaction of how far the bird would peck into the 'double wall' setup. I could see that the the Blue Tit 'image', if you consider the feathers a 'wall', this would imply it was only about 1-2mm 'peck distance'. Conversely, the Skull, which assume no feathers of soft tissue, would allow a 'peck distance' of say 7-8mm, which is fine. In truth, I suspect the reality is in-between the two - but it seems plausible to think a Blue Tit can get purchase on the nuts and feed. As the Great Tit is a larger beaked bird, this looks feasible too.

In truth, given the tenacious nature of Squirrels - I think hey may well aggressively thrust their gnashing teeth into the wires deeply - and may get further than I'd expected. With that said, it's possible that like any 'opportunist' omnivorous feeder, they may also just give up, and go eat something less strenuous.

And so, for all this theory and sketch-modelling - there is nothing left to build V2.0 and see how it performs.

Welcome to the process! Enjoy it if you are also at V2.0 - and Good Luck!!

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    9 days ago

    Excellent ! If only all teachers were this way, not just to educate but to inspire ! This ticks all my boxes as lifelong experimenter and inventer, and retired engineer, designer, and programmer in disciplines of electronics, mechanics and software. Now in later years I still recall key persons in my life who took time to convey their excitement, such as the visiting TV repairman (me aged 10) or the Applied Maths teacher (me aged 17). I hope your students realise the worth of their tutor. DON'T STOP !

    Hey Jude
    Hey Jude

    Reply 7 days ago

    Hi there, thanks for the great comment and enthusiastic support - it really helps. I suspect what is notable of your career, is that the tools may have modernised, but arguably much of the 'mindset' of experimenting, prototyping, and testing with people has not changed?
    As alluded to on the 'Wind Tunnel' project, I worked for a TV show, recreating props (Demo Rigs) of Great British Inventions, and even though some were 100+ years old, they still felt 'familiar' in may ways one would prototype today.
    The enquiring mind, as well as some skills to build and test seem universal....but are trails we need to support in schools, even though I sympathise they are hard to 'examine' in a tick box fashion. This will be the 'bridge', for sure.


    9 days ago

    Squirrels are very intelligent when it comes to finding food, but humans do seem to spend an inordinate amount of time trying to stop them. Nevertheless, I have found that a glass jar with a large ceramic plate on top and a small ceramic plate on the bottom, all bolted together with a length of studding through the middle, and hanging on a flexible wire, to be very effective at limiting the access of the squirrels. (Semi-circular holes in the bottom rim of the jar are sized to suit the nuts / seed and limit the amount the little 'burglars' can obtain.)

    Hey Jude
    Hey Jude

    Reply 9 days ago

    Yes - I agree that Squirrels are not very comfortable with Glass or Ceramic in general. I would use these (like Chris Notap), but for risk of sharp breakages, I opted for plastics, given the KS3 target age group. That said, mine is Polycarbonate, and still no break-ins!!


    10 days ago

    Marvellously on point Design and Tech project and happily eccentric in digressions (also very much on point for "mad inventors" and designers). I love your work and your attitude.
    Design, fail and rise again. It was ever thus. Keep up the good work.
    Here's hoping you inspire the next generation of designers/inventors.

    Hey Jude
    Hey Jude

    Reply 10 days ago

    I'll gleefully take "happily eccentric in digressions" - thanks!! =D
    I'm excited to see what other project people suggest as potential 'Level Ups' for D&T!


    11 days ago

    Do you get a prize for maybe the longest Instructable ever?
    We don't even have squirrels, but such a great 'ible, I read the lot.
    I would love to take on the squirrel challenge :o)

    Hey Jude
    Hey Jude

    Reply 11 days ago

    Haha - you have not read my previous ones. I think 75 steps is personal best ;o)
    That said, it's always a balance between brevity, but then having the necessary details for a noobie to follow it. The pro's can of course skim-read it, right, but I know myself some 'flashy' guides can miss out key steps.
    Anyway - hope you take on the challenge. My neighbour is now taking the brunt of disgruntled squirrels attacking their bird-feeder, after the 'Fortress' is too much for them!