Mini Cow Speaker USB Rechargable




Introduction: Mini Cow Speaker USB Rechargable

This mini cow speaker is first and foremost design a project to develop my product design skills. It would have been great to develop the project further and turn it into a saleable product but for now it remains a teenage dream. The following instructable will take you through the making stages of the cow speaker and also touch upon the packaging design and making. The speaker electronics have been adapted from an existing speaker. (The speaker packs a good punch for its size but if you require a speaker for a noisy party environment then I suggest you adapt the design). I like to have mine on when I'm at my desk working on projects. The speaker can be run off any portable music device with a 3.5mm audio output. It can be recharged using a USB mini cable. This speaker will run up to 6 hours from a single charge.

To make this speaker you will need:

  • CAD/CAM Software
  • CNC Router
  • 3D Printer
  • Laser Cutter
  • 30mm Solid Timber
  • 1.5mm Ply Wood
  • 3mm Acrylic
  • 6mm Acrylic
  • Bona Primer
  • Bona Mega Varnish Matte
  • Sand Paper
  • Wet and Dry Paper
  • Router
  • Drill
  • Pliers
  • Soldering Iron
  • Desoldering Tool/Pump
  • Solder
  • Toggle Switch
  • 22 gauge Wire
  • Tiny Brass Screws
  • Chassis Mount Female 3.5mm Aux
  • Hot Melt Glue Gun And Glue
  • Male To Male 3.5mm Aux Lead
  • Scissors
  • Centre Punch
  • Hammer

    For the packaging:
  • Grey Flat Pack Boxes
  • 100gsm A3 Card
  • Heat Transfer Foil
  • Silhouette Vinyl Cutter
  • 5mm Corrugated Card
  • Laser Cutter
  • Laminator
  • Guillotine

I was lucky enough to have access to a Laser cutter and CNC router at my collages Workshop and a good friend with a 3D printer I could use.

Step 1: Autocad

I used Adobe illustrator to create my
drawings. There are much better pieces of software but it’s all I had available at home. Illustrator is a vector-based programme and the line drawings can be saved as an EPS or SVG file and can be exported as a DXF format. I have provided 3 different formats for the routing files (dxf, eps and Ai) with the hope you can import them into any program you desire for milling. The laser files can be found under the 'Laser cutting' section.


The 3 files entitled Mini Cow CNC Router are 2 dimensional vector files ready to be imported into CNC Mill software (the software compatible with your CNC router). Each of the lines will need to have their tool-paths defined separately. I used a programme called GALAAD with my CNC.

1. Open up your mill software and enter the dimensions of the wood that you wish to machine. (Remember this is the wood that forms the casing of the speaker. It should be 35mm deep on the z-axis. The size of the x and y dimensions (width and depth of the wood) are up to you. How many cows you wish to machine?

2. Change the tool information to suit your routing bit and material. I used a 6mm straight 2 fluted router bit. I took 3mm passes in oak or 5mm passes in pine (I have a basic knowledge of the machine you can see in the picture BUT I am no pro at setting up any other machines so please refer to the speed and feed rate for you chosen material specific to your machine)

3. In your mill software define the tool-path to the inside or outside of the shape according to the diagram above (named: CNC Router Machining Depths .JPG). The diagram above shows the tool-paths I defined in GALAAD. Some of the paths are set to hatch/fill the shape and some are not. Some paths are set to cut on the outside of the shapes vector and some are inside. So… pay careful attention to my annotated sketch.


The laser cutter drawings are far simpler. Open up the drawings provided! You can either send the laser to cut directly from the illustrator software. Or import the dxf or eps file into your chosen laser cutter software. I imported my dxf file into CorelDraw 12, as it was the only programme set to function with the collages Epilog laser cutter. THE LASER CUTTER FILES CAN BE FOUND LATER ON...

Step 2: CNC Routing Parts

When you have defined
all your depths, feed rate, speed and tools in your Milling software you are ready to machine the Mini cow cases.

  1. Begin by finding suitable piece of wood- I tried elm at first and found it prone to splitting when machining. Slightly harder denser woods like oak and Iroko both worked well but feel free to experiment! The wood must be free from splits and knots. The router will not enjoy going through them!
  2. Ensure that the wood you choose is 35mm thick. You may need to process timber from larger stock with the aid of a band saw and planer thicknesser. Ensure that both sides are smooth and clear of debris.
  3. As the piece of wood is particularly large it will need to be secured to the bed of the CNC firmly. To do this drill and countersink clearance holes in the corners of your wood and screw it to the CNC bed using 8 x 2 screws. When the machining reaches the final cutting pass pause the machine and cows will need to be pinned down to prevent them from moving into the path of the router when the cow is cut free (see pins in photograph).
  4. Before machining rig up an extraction system. The cows will make a lot of dust!!
  5. Before you machine use a ruler to check that the screws are not in the routers path. Follow the Milling software prompts to start the milling process. This usually involves moving the router to the origin of the work piece, checking the settings and then pressing START.
  6. Then you wait.
  7. As mentioned previously when the machining reaches the final cutting pass around the outside of the casing the machine should be paused. The cows will need to be pinned down to prevent them from moving into the path of the router when the cow is cut free from the wood stock (see pins in photograph).
  8. Carefully remove the cows from the bed when done and sand down any rough edges.

Step 3: Laser Cutting

Below you will find 3 different files in 3 different formats.

  • File one contains all the parts to be cut from 1.5mm Ply Wood
  • The second has the Speaker Grill to be cut for 3mm Acrylic
  • The third one contains all the parts to make a Routing jig to be cut from 6mm (I will explain the jig later on).

    Please chose the format of file which works best with your Laser cutter program.

Power, speed and frequency of your laser should be adjusted to suit each of the materials. Laser cutter settings can usually be found online I found the settings for the Epilog laser here on page 211:

The photos above show the Cut out parts.

Step 4: Step 4: 3D Printing

A talented friend of mine won a 3D printer from an instructables competition a while ago and he was more than happy to help me try out new things on his 3D Printer. I wanted to create a snap in panel to house the usb socket and aux input.
I designed the panel in Autodesk Inventor (an excellent alternative to Autodesk Inventor would be 123D design- its free and there are hundreds of tutorials on the web to help if you are struggling to pick it up) . Below I have included the link to the stl file. Open up the stl in your chosen 3D printing software and follow the prompts to print.

Step 5: Routing a Hole in the Wood Case for the 3D Printed Panel.

This is the stage where the laser cut
jig from earlier comes into use. This jig is used with a standard router to make the recess for the USB Panel to click in.

  1. Take the 6mm laser cut parts and assemble them as shown in the picture above.
  2. Drop superglue into the joins and then for added strength glue gun along the outside of all the joins.
  3. Some of the plastic tags on the jig were proud so I used a flush cut saw to trim them flush and then sanded them down. This is imperative for the router to move smoothly around the jig.
  4. Place your cow speaker case in a bench vice or workmate with the cow’s bottom in the air.
  5. Slide the jig over the cow so that it sits firmly over the cow. The vice may need some adjustment. I like to have the base of the jig resting upon the jaws of the vice so that it doesn't wobble around (see photo)
  6. Ensure the jig is snugly over the cow, if it is too loose, use strips of thin cardboard to pad out the inside of the jig evenly.
  7. Insert a 3mm routing bit into your router. Then attach a 8mm guide bush to the router.
  8. Place the router on the jig so that the bush sits in the rectangular recess.
  9. Carefully rout around the perimeter of the rectangular recess. Take the cut in passes. Although the wood is only a few millimetres thick be sure to take it in no more 2mm passes to avoid breaking your wood. You are routing into the end grain and the end grain doesn't offer the same structure to support to the cut as vertical grain. (See animated GIF above).
  10. Once the hole is cut clean up the hole with sandpaper.
  11. Test the 3D printed panel fits the hole and make adjustments with a fine file and sandpaper accordingly.

Step 6: Finishing the Case

  1. Print out the paper template provided
  2. Cut out template fold along the red line.
  3. Position template on the cow.
  4. Centre punch through the template to make an impression on the cow.
  5. Drill two holes, one 3mm (for the LED power/charging indicator) and one 6.5mm (for the toggle ON/OFF switch)
  6. Sand down the wood casing. Work down the grades from P80 to P600
  7. Finishing the wood is entirely down to personal preference. I chose to finish the case with an amazing product called Bona Primer- an acrylic primer for use on floors. I chose this finish because it is particularly hard wearing and it keeps the woods colour natural. I dislike the turgid yellow colour that oak goes when oils or varnish is applied. However woods like cherry and walnut look beautiful with a coat of varnish, shellac or oil.
  8. Once primed lightly sand the case with fine wet and dry paper.
  9. Apply wax or varnish to finish. I applied a few layers of Bona Mega Matte Varnish.

Step 7: Adapting Circuit

The circuit comes from
some cheap speakers I found online: It worked our far cheaper to buy existing speakers than buying an amplifier circuit. Of course the cheapest option might be to make my own amplifier circuit, but even that would be a struggle to match the £2.68 speakers. I worked out the battery and speaker alone come to £6.00.


You have to be quite brutal to get the casing off. I began by twisting the two halves to open up the concertina. Hold on to the concertina and pull the speaker end off. Ensure that your pull is controlled- enough to separate the accordion and plastic but no so much that you rip the wires connecting speaker in the top half and circuit in the bottom. (See photo).

  1. Remove the speaker from the grill by pulling back the metal tabs. This half of the plastic casing can be disposed of now.
  2. Unscrew the 4 screws from the plastic ring that connects the concertina to the other plastic half.
  3. Use Pliers to cut and remove the ring that held the parts together
  4. Use pliers to cut the concertina in half and remove.
  5. Gently pry the circuit board from the case (there may be screws that need to be undone first)
  6. Cut the Aux input wire just before the jack and then pull the wire through the casing.
  7. Dispose of the remaining plastic casing.
  8. At this point you should have the entire casing removed.

Step 8: Soldering the Female Aux Input Socket


  1. Strip the end of the Aux wire and separate the three wires within.
  2. Tin the audio wires. I found the soldering iron had to be very hot to get the solder to bond.
  3. Take the three wires and solder them to the three tags of the Female Aux input according to the reference photo above. Gold to the outside tag and red and blue to the two bottom tags.

Step 9: Adding the Toggle Switch

Remove the existing switch from the PCB using a desoldering tool and soldering iron.

The switch removed (OFF-ON-ON slide switch) allows for two volumes settings.
ON=Medium volume
ON=High Volume

The switch I am substituting if for is a SPDT ON-OFF-ON Toggle switch

Follow the wiring diagram ABOVE to wire the switch to the circuit board. The wire I used was a flexible 22 gauge wire. I chose this wire as heavier gauge wires are more likely to rip the tracks from the circuit board when flexed due to the rigidity of thicker gauges.

Unfortunately I only had white wire in 22 gauge so I have created a colour coded wiring diagram above! ^^

Step 10: Assembly

  1. Begin by gluing the two pieces of 1.5mm Ply
  2. wood with PVA glue. Secure with bulldog clips and leave to dry.
  3. With a hot glue gun attach the speaker to the recess in the plywood panels.
  4. Hot glue the battery to the back of the PCB
  5. Fit the PCB into the casing. Locate the LED into the 3mm hole. USEFUL TIP: When pushing the LED into the hole. Be sure to push directly behind the LED on top of soldered legs to avoid ripping the tracks where the LED is soldered.
  6. Fit the 3D printed panel into the casing and glue in place. Ensure the USB input on the PCB fits into the slot of the 3D printed panel
  7. Fit the Female AUX input into the 3D printed panel and secure with the nut.
  8. Hot glue the wire coming from the female aux to the casing to prevent it rattling.
  9. Cut some packing foam into a small rectangle and hot glue to the casing behind the speaker. This stops the ply wood panels rattling when at volume.
  10. Fit the toggle switch into the 6.5mm hole and secure with spring washer and nut.
  11. Take the ply wood panel and fit into place (see photo).
  12. Pre- drill 1mm holes into the case where the ply wood holes correspond then screw down the plywood using 2x 3/8 brass screws.
  13. Snap the 3mm acrylic grill into place.

Step 11: The Packaging

I purchased some 'Grey A5 Ream Boxes'
off the web fairly cheaply (pre cut and scored) I designed some box inserts to hold the cow speaker as well as the audio lead and instructions etc. The box inserts are cut on the laser cutter form 5mm corrugated card, which I obtained from my local supermarket. I have included the laser cutting files for the box inserts. The file also suggests how many of each layer to cut. Once cut put all the layers of card into the box

The box wrap packaging was designed in Adobe Illustrator and then printed on A3 white card using a toner printer. I specifically used a toner printer, as I wanted to try out some hot foil transfer. You will notice that parts of the printed surface are shiny. I achieved the shiny effect by the following steps.

  1. Take your A3 card with printed image and place heat transfer foil over the areas of toner where you want the ink to shine. If necessary you can use a very low tack masking tape to hold the foil in place at the edges
  2. Fold a sheet of non-stick baking paper around your A3 card. This prevents the foil getting caught in the laminator. (It acts as the laminating pouch)
  3. Finally send the sandwich of paper through a household laminator set to hot.
  4. Remove the baking paper and peel away the foil. The foil will have stuck to the areas of toner ink.

There is a much better description of the process here:

Most videos suggest that you have to have a
specific foiling laminator for the job. I used a standard A3 laminator from my local Tesco store and it worked just fine. The laminating pouches are not essential either- as mentioned above I just use baking paper folded in half.

Once foiled the packaging can be cut out. I used a vinyl cutter plotter to cut mine out precisely. But a pair of scissors and guillotine would work equally as well. I have included a PDF showing where all cuts and folds should be made.

Step 12: Demo/Test

In response to eblair420's very important question question "Is it for sound or sight?". Heres a little video to demonstrate the sound quality of the Mini Cow Speaker. The sound quality is only as good as the iPhone I recorded this video on, but hopefully this shows that the speaker is clear and free from crackles and distortion at full volume.

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    7 years ago

    Is it for sound or sight?

    (PS 4 sale?)


    Reply 7 years ago on Introduction

    Good question! For it's size I'm very happy with the quality of sound. The original speakers I adapted to make this cow speaker from were prone to distort at full volume.... I have managed to refine my cow speaker so that it produces a richer louder sound. Even at full volume and high frequencies the distortion is now barely if at all noticeable! I have made a little video with different music types for you to demonstrate the speakers clarity so you can form your own opinions:;

    To get the best from the cow speaker ensure the speaker is properly padded behind with foam (as discussed) and all components are screwed , glued or soldered securely. If parts aren't secure the high frequencies will vibrate the parts and make unpleasant sounds and bad solder joints won't help either . Admittedly you won't get hi-fi clarity and volume with something so small. But for use when working, pottering and tinkering on projects it fulfils all expectations. I hope this helps :)


    7 years ago

    Hey, I think this is awesome! Perhaps I missed it in your instructable, but is there a place I can buy it pre assembled? I really liked this so I voted for you! I hope you win something!


    Reply 7 years ago on Introduction

    Thank you for your kind words and for voting for me! I would like to produce more in the future. I don't have the machinery at my disposal to make the cows anymore. However I'm going to get my head in gear and look into the possibility of making them on a larger scale, or just small batch runs. I will be sure to let you know! :)


    Reply 6 years ago

    Also interested in a batch run


    7 years ago

    wow. this is awesome. thanks for putting this up.


    7 years ago on Introduction

    This is an awesome ible. Really loved the way you taken those alien looking speakers to a very earthy(milking) one. Execution, presentation was awesome. And final product is a hell sleek one. Position of AUX & on off switch is also well thought of. All in all you are awesome the packaging too flabbergasted.


    7 years ago on Introduction

    I fully expected this to be one of those vague, borderline advertisement 'ibles and was pleasantly surprised. A ton of good info, thanks!

    Did you use the optical eye for cutting it on the Portrait or simply loaded it as straight as it goes and it was fine? I'm still new and confused with my cutter.


    Reply 7 years ago on Introduction

    There are registration marks on the image in three corners. The Vinyl cutter can be told to detect the registration marks and then it will know where to cut. I think this is the information you are after: .


    Reply 7 years ago on Introduction

    Thanks, now that you told me I can clearly spot the registration marks in the pictures. Will have to check if this function is also available in SCAL as I use that instead of Silhouette's own software.

    I live in a town where we have a holiday called dairy days this is a perfect thing for it awesome


    7 years ago

    That is rad. I too would without a doubt buy one if I found this on a store shelf. I can't imagine making any changes to the design at all. Perhaps Bluetooth would be cool though. Awesome build.


    7 years ago

    If you have some space left in that cow you could instal a bluetooth receiver in it ;) awesome product


    Reply 7 years ago on Introduction

    Could put it right in the mouth

    make a blue tooth to hide it in


    7 years ago

    The case can also be made by several identical layers of plywood. These would need to be glued, on on top of another. This, after sanding, polishing would yield a more attractive product, imo. Like the idea of using ready made speaker parts. Very economical. Excellent overall idea.


    Reply 7 years ago on Introduction

    thanks. I really want to make something like this for my sister but don't have the router or 3D printer (though can find a local if I look hard enough) Do you know of any instructable showing something similar done with plywood?