Introduction: Large Vacuum Former

Picture of Large Vacuum Former

We had a requirement for a big vacuum former, as many of our members were interested in costume making and cosplay and needed to be able to make torso size "armour" etc. so we first took look to see what was available commercially and soon realized anything we could afford even second hand would be way too small for our needs. Having decided that our only option was to build our own we scavenged the internet for ideas and came up with a basic design that evolved into the machine we have made.

Step 1: Building the Vacuum Table

Picture of Building the Vacuum Table

So first the simple bit, all the vacuum table really is is a hollow box with a way of drawing a vacuum and a grid of holes. We opted for constructing it out of MDF, but any strong sheet material would work. Your next problem is to decide how to drill the holes we opted to use a doweling jig but you could get them cnc routed.

For legs we used some steel ones from Ikea that we had in our donation room, but timber would be possible. This thing is heavy so rather that rely on screws to hold the legs on we bolted them on using Tnuts. You will also want to reinforce the box, the air pressure acting on the out side of this box will want to deflect the table and make it concave. However you choose to reinforce the table make sure your reinforcments do not restrict the air flow too much, we drilled 75mm holes in ours.

Step 2: The Heat Source

Picture of The Heat Source

We had originally intended to use nichrome wire for the heating unit but found it a little difficult to get hold of at a reasonable price in small qty. After a bit of thought we decided to go with halogen GU10 lamps they are woefully inefficient when it comes to light which means they dump out a lot of heat.

We explored various mounting options but soon found the most cost effective was to purchase ceramic GU10 lamp holders (we made the mistake of ordering the exact qty we need, unfortunately one was smashed on delivery so its worth getting a couple extra just incase) and mount them to a sheet of steel with self tappers. The steel sheet came from the back of a shelving unit we had lying around although once again you could just purchase some from you local metal stockist.

We then faced the nightmare of 70 lamp holders, 2 wires from each that need to be wired together. everything from terminal blocks to soldering the wires to each other was considered but in the end we decided to make a basic PCB. Due to the size of the PCB we were unable to etch it in house and the usual companies proved too expensive. In the end we manually milled them.

Due to the width and thickness of the tracks you will require a very powerfull iron to solder the wires from the lamp holders in place. You will also need to mount the PCB's we opted for using simple mounting pillars.

This everything was then enclosed in an MDF box with a ledge to support the steel plate and a removable lid for servicing and repair. At the moment it seems to be remaining cool enough but if we find its getting hot we will add ventilation.

Step 3: The Controls

Picture of The Controls

Whilst investigating the options for the heat source, we talked about the possibility of being able to heat specific areas of the vacuum bed in order to reduce power consumption when accomodating different sized work pieces. As we had originally planned to use nicchrome wire, this ability would have been limited to being able to switch on perhaps two different lengths of nichrome to give half and full power in similar way to a cooking grill. With our choice of heat source being a large array of spot lights arranged in rows and colomns we have much greater flexibility in terms of controlling both which areas of the vacuum bed recieve heat and how much. However, this greater flexibility does make the control system more complex since it now requires relays to switch power to the rows and colomns and an AC phase control system to regulate how much mains power the whole array recieves.

The control system is composed of six major component parts: Front panel assembly, Microcontroller PCB, AC phase control PCB, Row Relay PCB, Colomn Relay PCB and Triac assembly for vacuum plus heat.

The front panel assembly is made up of an PCB mounted LED matrix corresponding to each heating element in the array, an alphanumeric LCD for system status, a key switch to enable the machine, an emergency stop button and switches to select the various heating patterns available.

The microcontroller PCB contains an Atmega644 device that runs custom firmware written in C for controlling the machine. This PCB has inputs from the front panel switches, temperature sensor within the heating array and pressure sensor within the vacuum bed. It outputs digital signals to switch the row, colomn and vacuum relays and a PWM output to control heating power. The status LCD is also driven from the microcontroller.

WARNING: The following components connect directly to 240V AC power.

The AC phase control PCB takes the PWM output from the microcontroller and provides triggering pulses synchronised to the AC line to a Triac switch, by controlling the point during the AC cycle when the Triac fires it is possible to regulate how much power is supplied to the load, in this case the heating array.

The colomn relay PCB consists of six electromechanical relays driven by the digital signals from the microcontroller, five switch power to the rows of the heating array and a sixth switches power to the cooling fans.

The row relay PCB has seven electromechanical relays driven from the microcontroller that switch the neutral to the rows of the heating array, it also contains a temperature sensor to monitor the temperature within the array.

The Triac assembly is made up of two opto-isolated triac solid state relays, these are rated at 20A, 240V AC and control the power to the vacuum fans and the heating array.

Step 4: The Clamping Frame

Picture of The Clamping Frame

Right from the start we wanted to be able to use this vacuum former for big sheets (600mm x 900mm) of plastic but we were aware that most of what we would do would be much smaller so we want the clamping frame to be able to work for all sizes from A4 up. For the larger sheets we have opted for a large frame made of two sheets of mdf with a 600 x 900 hole with the holding force coming from wingnuts and tee bolts. If you wish to form a smaller sheet you can replace the bottom sheet with one mounting either a toggle clamp frame for the common sizes or additional wing nut frames. To aid sealing of the frame to the table and the sheets to the frame we have used foam tape.

Step 5: The Vacuum Source

Picture of The Vacuum Source

Finally we needed to find a source of a decent vacuum. A search around in our donation room found a couple of vacuum motors which we believe had came from a garage forecourt vacuum cleaner. As we had these we decided to go with them but if you cant get any a powerful domestic vacuum or shop vac would be a good substitute. Using these did however pose a problem as there was no easy way of mounting them. In the end we drilled a hole in the bottom of the vacuum table, and with a neoprene gasket in between clamped them in place with a MDF clamp plate and all thread. For now these have been left exposed but will need to be enclosed with some form of vent to allow the air to flow out.

Step 6: Final Assembly

Picture of Final Assembly

You should now have all the key parts of your vacuum former, all that remains is too bolt everything together. We decided to use Unistrut to link the vacuum table to the lamp box and to act as the guide rail for the clamping frame, as we already had some left over from the previous project. The clamping frame runs on Unistrut bearings which were salvaged from a sliding barn style door.

For now we are relying inserting pins through the Unistrut to hold the frame in position below the lamps but in the future we may add a counter balance system to aid sole operation.

Step 7: Testing

Picture of Testing

So the moment of truth. As we did not have a mould to hand we laid some tools out on the bed to spell out fizzPOP. We clamped a sheet of Hips in the frame and raised it up next to the heat source, we soon noticed that we were getting a warm spot below each lamp (our first attempt ended up with thin spots). Lowering the material further away from the heat source by a few inches resulted in a much more even heat. We allowed the material to come to temperature turned on the vacuum motors and quickly lowered the frame over our "mould".

Other than around the edges were the frame had both shadowed the material slightly and also conducted the heat away we go a very crisp and detailed form with very little distortion. If the future we may look at adding reflective tape around the edge of the frame to try and reduce the shadowing effect.

Step 8: How to Operate

To help clarify a couple of point and answer some of the questions in the comments, below are instructions on how to operate the vacuum former.

  1. Clamp your plastic sheet in the frame.
  2. Raise the frame to the appropriate height below the lamps and support by inserting the pins through the slots in the Unistrut.
  3. Turn on the lamps and allow the plastic to soften (this will take between 30sec and 5min depending on the material). Do not walk away when the heating lamps are on!
  4. Position your mould on the vacuum table.
  5. Once the plastic is heated sufficiently (HIPS will tend to warp to start with, then go taut then sag slightly) turn on the vacuum system
  6. Pull the pins and by hand push the frame with the now softened sheet down over your mould until the frame makes contact with the vacuum box.
  7. The sheet should rapidly be drawn down around your mould.
  8. Turn off the lamps and vacuum system and wait for your moulding to cool before removing.

Hopefully that should make things a bit clearer.


vissermatthijs (author)2016-09-15


We (RDM Makerspace are also making this vacuum former. The problem is the heat source doesn't get warm enough the plastic wont melt properly. The lamp we are using is the GU10 halogen 50 Watt 230 volt.

1. Is the lamp we are using the correct one?

2. What is the distance between the lamps? We are using 100 mm.

JACKD16 (author)vissermatthijs2017-01-05

Try using 1500 watt quartz element heaters, enclosed in overhead or under lid-in box below. depending on your design this is your best inexpensive option.

Vecmaico (author)2016-09-01

So, what's the electricity bill after one year of daily usage?

frankhall (author)2016-06-16

Looks nice

Mack010205 (author)2016-05-21

Hi could you build a large vacuum former for a company in cheshire?

We do do commercial work, give us a ring and we can discuss your requirements. Our contact details are on the website.

Hi Stuart could you contact me on 07931222240 and leave a voicemail if it goes to answer phone and I will get back to you thanks Steve

Hi Stuart I can't seem to find a phone number for you, could you send it to me then I can call you Monday, thanks Steve

Ok thank you I'll be in touch Monday thanks Steve

Technoaussie™ (author)2016-05-08

The concept of vacuum forming hasn't changed much since it first became a manufacturing process. Heat some thin acrylic sheet and suck it down on a mould. My variation is to force it down on a mound with warm compressed air. Basically the same but different.

The largest piece of plastic I have ever formed was a 6 foot long boat! Sadly it was too thin to handle the waves created by an outboard motor and had to be re-enforced with timber before it became practical.

My comment on this instructable is cost related. The larger the sheet you heat, the more electricity it consumes. Electricity in Australia at any rate is horrendously expensive. I blame past Governments for their greed in not building infrustructure for the increased population paying them taxes.

Anyway... I solved my electricity needs by developing a solar/storage system and changing to propane gas for heating. It's now quite practical to create a very efficient oven using Barbecue gas burners! The cost is now within an affordable range for projects like this one. My vacuum mounting press (for mounting photos to backings without bubbles) is 6 feet x 4 feet. I use the vacuum pump from that press to create a 10 cubic feet store of vacuum that when enabled will suck down most items in a second or so... Provided any edges are carefully holed to prevent bubbles forming.

The next holidays and I'll make an instructable about it.

nandohaze (author)2016-05-05

some idea about the specific suction power needed (like a domestic vaccum with X watts, or even a car vaccum)? i try to achieve a smaller version´s vacuum former

thank a lot!

James TaylorT (author)2016-04-13

please could you e mail me would you be able to make me one 2ft x2ft? this is for a very very special reason please e mail me at

DanC71 (author)2015-11-21

Awesome build. I am a little confused about the heating lamps what voltage do you run them on ? How hot does it get ? and how thick of material have you done in your machine ? Thanks

PaulM108 (author)2015-09-08

What sized vacuum motors did you use? Do you think two 14gal Ridgid shop vacs would work? (HD's website says they are 6 peak HP)

EliH6 (author)2015-09-01

Do you have a list of materials you guys used, sites you ordered from and total cost of the project? Me and my friends are working on setting up a prop and cosplay repair shop and this is exactly what were trying to build! I would love as much information on this project as possible. Also, we may use a shop vac instead.

Hi EliH6

The vacuum former was made largely from materials we already had around the hacker space, we are based in the UK so a list of suppliers is most likely not going to be of much help. I think the only things we purchased were the sheets of MDF and the lamp holders.

I would think you could build this for around £150 or $230, if you have much of the material already like we did it will be much cheaper. If you have any particular questions we would be happy to answer them.



DeadlyDad (author)2015-04-17

Nice build! One idea is to have an 'oven bottom' frame that mounts under the sheet frame, and have fans to circulate the air between top and bottom sides of the sheet for more even heating of both sheet sides.

FWIW, I'm planning on building a piston-type vacuum source for our makerspace that uses 6 of the 5' high-pressure gas cylinders( with the tops cut off), with the piston rods connected to a common bar that is attached to a 3 ton winch. That should provide a tad of vacuum, wouldn't you think? :grin: (To be honest, I'll probably have to scale it back just to keep it safe.)

NathanSellers (author)2015-04-04

Nice work. This looks fantastic. Great design. If only I had more time on my hands... These things are so handy.

Thanks for your kind words. I don't think this would of got done nearly as quickly if it had not been a group project at the maker space.

jayeshshinai (author)2015-04-11


Whats the electricity consumption using the bulbs?

The heater draws about 3.3Kw. Not sure about the fan and controller.

Parkerc234 (author)2015-03-28

Hey guys, I want to to make a small size shed size? Is this possible?

This design would scale down pretty easily, however there are many other designs out there for smaller vacuum formers, how big do you want to go?

I want to make 4m x 4m then about 2 meter high so pretty big? Is there machinery out there that could create some thing on this scale

I don't see why you couldn't go that wide but a 2 metre draw would be a real problem. Its also worth noting the forces over that kind of area would be huge!

walshlg (author)2015-03-15

I want to lay down on it and vaccu-form my torso! Anyone ever try that - sort of a torso frame? Could use some sort of rubber gasket I suppose around neck and abdomen and arm holes. Hot stuff would need to wear a sweat shirt too.

I am pretty sure that would be a bad idea! The plastic does get hot enough burn and even if it did not breathing would be difficult to say the least, lets face it the effect would be not dissimilar to an iron lung. To achieve the end result I would suggest making a life cast and then casting a positive form from that which you could them vacuum form in the normal way. Hope this helps.

yes I suppose I was letting my imagination run away with me. Besides just to make a torso frame would be a lot of crafting and would essentially require a 2 step molding - once to get the plastic into a generic shape for the body contour mold and then live molding onto your torso. You could only do it over heavy clothing and certainly not directly on skin, making me question my idea as to what is the use of molding if its a bad fit?

Great stuff, our makerlab is going to go tour one of the group's large molds next weekend. Thanks for the instructable!

Kinnishian (author)2015-03-10

I am a little uncertain how you lower and raise the hot plastic sheet- is there some sort of rail? And then do you drop the clamped plastic by hand over your mold and apply vacuum?

Hi Kinnishian

Just looked and you are right the operating procedure is not very clear, we will add another step describing it as soon. in the meantime to try and answer your specific questions; The frame with the sheet is held below the lamps by pins inserted through the Unistrut rails that the frame runs on. When you have the plastic heated sufficiently you turn on the vacuum system, pull the pins and by hand push the frame with the now softened sheet down over your mould until the frame makes contact with the vacuum box.

Hope this helps


Cool! Thanks! :)

And what stops the frame from crashing down too quickly after pulling the pins? Is there enough latent friction on the frame-to-rails boundary?

I think I get it now. I appreciate the clarification

Currently it is just the friction in the system, we had intended to set up a counter balance system but so far it seems un necessary, we may have to re evaluate once things have had a chance to ware in. As a general rule we have one person at each end anyway so the lowering can be pretty well controlled.

PhantomX999 (author)2015-03-08

If i'm understanding you terminology well enough and the problems you're having. You're getting some spots that aren't getting enough heat while some others are getting too much?

Maybe try having your lights in a alternating pattern were they're more packed together instead of your checker grid layout.

That was on our first test form. We find if we do a slower heat from a bit further away it is uniform enough that we can't notice any difference in the material.

well, i'll definitely consider this for my first Vac former. I'm not too keen on using a toaster oven for heating. with my luck there would be fire.

krieglers (author)2015-03-10

That's power source is absolutely Brilliant, because it's so simple. Ni-chrome wire is great but the Halogen will produce enough heat, to heat without the need for extra breakers in the distribution board. Thanks for the brilliant idea, best of all the lights are pretty cheap in Bulk.

Chopper Rob (author)2015-03-05

Does this work with acrylic? If so, how think? I have an order for a see-thru automotive differential cover and I think your machine may be my solution.

DouglasJ1 (author)Chopper Rob2015-03-08

To chopper Rob.

You might find a different method for making the transparent diff housing will suit better. I've got a Vacuum former and I work with acrylic shapes a lot. I often 'blow' heated acrylic sheet against a shape to produce things like you want. I'd recommend heating a sheet in an oven until it becomes pliable and them (using hot air) with the floppy sheet held in a frame, blow it into the diff cover if its only made from sheet metal. The result will be smaller by the thickness of the acrylic used but if you use 3mm it may fit because of flange also being 3mm further away from the crown wheel.

If you still want to use vacuum, making the mound to suck the sheet into is going to take a fair amount of craftsmanship, not to mention the amount of suction you'll need to pull it into shape. Everything to do with forming acrylic sheet has to be done during a narrow range of temperature... That means quickly. My vacuum pump takes quite a lot of time to reach ultimate suction. Keeping something hot enough in a frame as large as fizpop's until a high vac pump reaches enough suction would take my pump at least a minute and a half Too long to keep acrylic pliable.

2wice2 (author)DouglasJ12015-03-08

What about using a vacuum receiver 2 x the volume of your former cavity and when you reach GT temp dump the air into the receiver all at once?

DouglasJ1 (author)2wice22015-03-09

I once used an Air compressor tank to create a reserve of vacuum to pull down a pair of valve covers for a 302 V8 engine... One at a time. Wastage during experimenting can be quite high (and expensive).

I ended up using 2, 8' x 4' sheets just to get one pair of perfect covers. I don't recommend this to anyone without a determination to succeed and deep pockets.

Just making a mould (I used fiber glass) took me a week and 3 tries to get one strong enough to withstand the almost instant suction of opening the tank valve. Calculating the oversize amount for a mould – so the thicker covers cleared the valves was a mathematical nightmare for me. I have trouble with pi, let alone algebra. All just to win a $10 bet that I could do it!

SolidRaven (author)Chopper Rob2015-03-08

Even with commercial machines forming acrylic and polycarbonate is nasty at times I've found. At least our desktop machine at work (+/- A3 format) has issues with uniform heating of large sheets quickly. Found an easy trick to get it done properly though! Since you should pre-dry these materials anyway I've found its best to put all the sheets you want to use in the oven early in the morning, and wait until they're dry. Then warm-up the machine and in the meanwhile raise the temperature of the oven to something close to the glass transition temperature of the material so the sheets don't need much additional heating. It requires quick working, which might be tricky with the clamping frame on the machine presented here, and good thermal gloves but it tends to give better results I've found. But if you can, stick to polystyrene. Very easy to form and very cheap. :)

Hi, we have not tried it with acrylic yet. There should be enough heat the only issue would be that acrylic is not that stretchy so is better suited to a high vacuum set-up, having said that depending on the level of detail required you might get away with it. We do have some clear HIPS and will be trying that soon.


Dzacher (author)2015-03-09

Wow great job!!

I have two suggestions that might help with vacuum problems.

1. I have found that a strong vacuum actually pulls air through MDF - we use this property to hold thin sheet material down on a Shopbot at my work. Because of this, you may want to paint the outside of the vacuum box, that could give you a stronger pull on the top.

2. I think a combination of Shopvac combined with a higher pressure vacuum pump works really well the Shopvac pulls a lot of air volume when the plastic sheet is brought down, the high pressure vac then pulls that last bit of air.

Also side note the top often gets crazy hot you may want to make that out of sheet metal instead of MDF for fire safety.

Just my 2 cents - this is a great project!!! I'm really impressed.

paulstaf (author)2015-03-08

What about using the heating element out of an electric clothes dryer? I am sure they can be had brand new for under $30.

ferd_berfal (author)2015-03-08

Nicely done. You might reduce the uneven heating problem by closing off the open side space between the plastic carrying frame and the heat lamps. You've basically built an oven without any sides and air flow from the sides will tend to cool the edges. Close off the sides of the oven, and perhaps even add a small fan off to the side to circulate the heated air, and I think your uneven heating problems will be greatly reduced. The sides don't have to perfectly seal, you just want to reduce the couple square feet of open-side surface down to a more reasonable value of say a few square inches. With the sides closed off you can probably increase the light to plastic distance (further reducing uneven heating) and perhaps even use fewer lights.

Dark Solar (author)ferd_berfal2015-03-08

what ferd said with maybe the addition of a bit of 30 gauge plate between the lights and material holder that is painted black on the lights side and copper plated on the material side to allow closer proximity to the heat/shorter softening time?

Thank you for your input. At the moment with the increased distance its working well, but we may however look at closing off the upper section in the future, particularly if we need to work with heavier materials. Currently it relying very much on the radiant heat.

damianzuch (author)2015-03-08

nice work! we've been trying gather info about building one of these, this is perfect! say, do you think it could work with one of those think plastic sheet Fresnel magnifying lenses? i want to try forming one of those around a plaster face to make a mask.

GarethHay (author)damianzuch2015-03-08

So far we have only used HIPS plastic so far. Will update if anyone has success/tries with one of those lenses.

RedBinary (author)2015-03-08

Very nice! I would not have guessed that halogen lamps would have been enough heat! What kind of heat time does it require?

I work in a plant with a large vacuum former and a few years back I was responsible for designing a new heat controller for it. It uses heaters that are nichrome embedded in ceramic switched by mercury relays. The mercury relays are in turn switched by SSRs. I wanted to use as much of the existing control hardware as possible to limit costs and it has proven to be very reliable over an extended time. I had not thought of the timing methodology you guys used, but it would not have been possible with the system we had anyway. So I used the same timing methods as the old controller: Determine a heating cycle time - typically 2 seconds - and vary zones by a user-specified percentage of that time. There is and additional parameter "compensation" that is applied to all zones. This is an additional percentage of the zone percentage - this is a very effective way to allow quick adjustment of the entire sheet. I found the way they handle the high output density with just a few output lines very clever, it's basically a memory structure. Here is a very boring write up: It may be worth noting that this was several years ago and I was rushed to get the initial installation in place. I've since done away with the intermediary communication kludge and now directly communicate with the touchscreen from the controller.

About This Instructable




Bio: We are a small UK hack/makerspace. Wide and wild variations in interests. This is our official account. Open nights on Wednesdays. See @fzzpop, www ... More »
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