Make a good, cheap, upgradeable sheet plastic vacuum former

Picture of Make a good, cheap, upgradeable sheet plastic vacuum former
Tired of buying cheap plastic crap? Now you can make your own!

Or you can make nice and surprisingly sturdy plastic stuff in amazing shapes, amaze your friends with your technical prowess, and be the life of the party.

Vacuum forming is a technique for shaping sheet plastics into 3D shapes, which you can do at home, easily and cheaply. And it's fun. It's the easiest way to make an infinite variety of shapes in plastic, or to make molds for casting shapes in other materials, such as concrete.

The basic technique is to

0. clamp a sheet of plastic to a frame (such as a windowscreen-type aluminum frame)
1. heat it in an oven (such as your kitchen oven) until it's soft and rubbery
2. stretch it over a convex mold of an interesting shape (such as a life cast of your sweetie's face), and
3. suck the plastic inward onto that mold with a vacuum system (such as your household vacuum cleaner)

Once the plastic cools, you pull it off the mold and trim off the excess plastic, leaving a copy of whatever shape you sucked the plastic onto.

In this instructable, I'll show you how to make a cheap but good vacuum former, using mostly things you have around the house, or can buy very cheaply. The whole thing shouldn't cost more than about $30 to $50, maybe less depending on what shortcuts or substitutions you choose, and what materials and tools you have lying around. It also shouldn't or take more than an hour or two to make. (Plus a shopping trip to a home improvement store and an office supply store, and letting some silicone cure overnight; you can use epoxy if you're in a big hurry and want to do it all in an evening.)

Here's a movie of the vacuum former in action:

Relatively few people know about vacuum forming, or how easy it is. They're mostly radio control model builders---who use it for making thin plastic parts for airplanes, or bodies for cars or helicopters, or hulls for boats---or they're Star Wars fans who use it for making their own costume armor.

It's unfortunate that vacuum forming know-how is mostly limited to these little niches, because vacuum forming can be used for many purposes, artistic and practical. If you like making stuff in general, and especially if you like non-rectilinear stuff that doesn't look "homemade," you should know how to vacuum form.

You can use vacuum forming to make:

1. intermediate molds for modifying and combining sculptural shapes (this allows you to sculpt in whatever medium is easiest, and transfer the shapes to plastic, making one copy or many)
2. sturdy custom parts out of thick plastic to protect delicate machinery. (Using cheap homemade equipment, I've vacuum formed shells from 1/4" thick plastic that are sturdy enough to stand on.)
3. three-dimensional, internally-illuminated signs from scintillating textured plastic
4. flexible, cushiony custom liners from thermoformable foam
5. relief sculptures of various kinds
6. molds for casting chocolates, soaps, candles, or concrete relief sculptures
7. decorative architectural reliefs, or decorative shells that can be reinforced for structural purposes
8. stage props and costume parts in hard plastic or soft foam,
9. zillions of things you'll probably think of.

Industrially, vacuum forming is used for making all kinds of things, from disposable plastic cups and lids to sinks and hot tubs and McDonald's golden arches to full-sized boat hulls. (If you've never seen a 30-foot sheet of plastic sucked into a boat shape in a few seconds, trust me, it's pretty cool.)

For vacuum forming at home, the main limitation is usually space for the equipment---the size of your vacuum former is proportional to the size of plastic sheet you need to form. The $30-50 vacuum former described here doesn't take up much storage space at all, and can handle thin plastic sheets as big as will fit in your oven.

For larger stuff, you need a custom oven---not very difficult or expensive to make, but a little bigger all around than the plastic it will heat.

For thick plastics (more than about 3/32" or 1/8" thick, depending on several variables) you often need a stronger vacuum than a vacuum cleaner will provide, and again the cost and size of the equipment are roughly proportional to the size of plastic sheet you will be forming. The cost can be under $50 for a high-vacuum system for thick plastic sheets up to about 12" x 18", using a converted bike pump, or an electric air pump of some sort from a thrift store. (Such as a kitchen vacuum sealer, a tire inflator air compressor, or a "nebulizer" air pump.)

The vacuum former described here will work very well with an inexpensive high vacuum system, getting professional quality results for thick plastic, for under $100. If you want a standalone vacuum oven, so that you can use it somewhere besides your kitchen, you can make a medium-sized one (12 x 20 inches) for $30.

For now, let's make a good fast cheap vacuum former that you can do a lot with, using your kitchen oven and vacuum cleaner; it's mainly a board with a hole in it, which you can store on a shelf. You can soup it up later, if you want.

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snowpenguin5 years ago
drcrash (author)  snowpenguin1 year ago

A single layer of soda bottle plastic often works really well and eaisly for small stuff like most model plane "bubble canopies," and for smallish food molds like chocolate molds or jello molds. (It's "food safe" plastic unless you burn it.)


drcrash (author)  snowpenguin1 year ago



shotgunefx7 years ago
drcrash (author)  shotgunefx7 years ago

I made a quickie vacuum former awhile back out of parts laying around the house, I had an expanded metal shelf laying around that worked for a base.



Thanks again.
drcrash (author)  shotgunefx7 years ago
n0ukf6 years ago
Gnome n0ukf6 years ago
TechDante6 years ago
drcrash (author)  TechDante6 years ago
HaZe327 years ago
drcrash (author)  HaZe327 years ago
ovechkin0807 years ago
drcrash (author)  ovechkin0807 years ago
That depends a lot on what you want to make.


I'd recommend starting with plastic between 1/32 and 1/16 inch thick. (Or .030" to .060" or so.) Thinner plastic cools so quickly you may have trouble getting it to the platen and formed before it cools. Thicker plastic is harder to form without high vacuum, and is more expensive.









You can get a piece of PETG about 6" x 13" (IIRC) by splitting cutting the ends off a 3-liter soda bottle, splitting it, and unrolling it. A lot of RC plane "bubble canopies" are made of pop bottle PETG.


rerat7 years ago
drcrash (author)  Erik Lindemann7 years ago
drcrash (author)  Erik Lindemann7 years ago
Right. Many holes, in themselves, don't hurt, and they are actually a little more convenient---you can use very short "spacers" such as a single layer of window screen to keep the mold from blocking the holes under it, and to keep the plastic from sucking down flat over the holes around the mold.



Here's a posting over on that sketches how to make a many-hole platen that won't collapse under vacuum and doesn't hold a lot of useless air:





Thank you, very informative.
drcrash (author)  rerat7 years ago
marcwolf5 months ago

This has always been a hinderence re drilling lots of holes.

Peter_Pan7 months ago


Well NOT so!!! Because I now realize that whether I used holes in my platen, or a window screen as you suggest, the "lip" surrounding my mold is probably going to look awful, having the window screen pattern now molded into its surface! I'm not sure what to do about this. I guess I could just live with the screen pattern and try to sand it off
the end.




bgepp110 months ago
feyr5 years ago
drcrash (author)  feyr1 year ago
drcrash (author)  drcrash12 months ago
And don't forget that shop vacs are no great shakes for vacuum forming. They generally DO NOT suck any harder than a canister vacuum, and they're awkwardly big with awkwardly big hoses. Ratings like "5 hp" are a bullshit. A shop vac doesn't generally draw more current than a good household vacuum, so it CAN'T generate more power without blowing your fuses or flipping your circuit breakers.
keenan6 years ago
keenan keenan6 years ago
sorry I meant oven timing duh
drcrash (author)  keenan6 years ago
hi- very nice project, well thought out and applied !! i have a problem i'm hoping someone can help me with. i'm doing some prototype work and for the life of me am unable to find a source for plastic sheeting that is within reason. i need a source for two types of plastic sheets. the first one has to have the properties of being aprox. at least 18"X18" and have a little strength to it. the second one about the same size or bigger and similar to the to the dome plastic used in grocery store bakery items. what i have found in searching is the price is simply wacko. i am now considering re-purposing things like large pvc water pipes, and such. as far as the dome stuff i do not have any ideas that are good enough. anyone out there have any thoughts ?? thanks
drcrash (author)  cmjake00712 months ago
You can get 4 x 8 foot sheets of plastic from a local plastics supply store---they sell sheets of various plastics to sign stores, contractors who use them in construction, etc. It's much cheaper per square foot than buying plastic from a hobby store or hobbyist supply place.
I've been looking, too. So far I've only found

but they seem a little on the pricey side. I'm still searching for a wholesaler. Anybody got any leads?
drcrash (author)  keenan12 months ago
For thin plastic, I'd generally adjust the heat until the plastic softens up and sags enough (about 1 inch per foot of span the short way) in about two minutes.

You can heat thin plastic faster than that (and industrial systems do), but keeping it fairly slow is nice in a low-volume low-end home setup, for a couple of reasons: (1) it gives you a little more slack for misjudging the time, and (2) it lets the oven air circulate a bit and even out the heat, after opening the door to put in the plastic, or if you open it to check on the sag. (It's better to look through an oven window if you have one.)
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