Introduction: How to Make Your Own Prototypes : How to Make Your Own Plastic Vacuum Former

Picture of How to Make Your Own Prototypes : How to Make Your Own Plastic Vacuum Former
Make a Plastic Vacuum Molder using parts around the house.

NOTE--This article was originally posted at SheekGeek. This is my first tutorial or instructable.

Plastic vacuum formers are an important part of prototyping. If you need a nice plastic robot body, or custom case for a project you are doing, get your tools, 'cause this one's easy to build and fun to play with.

The vacuum former uses a simple concept. They use the power of a vacuum to suck gooey plastic sheets very tightly around an object you place in them, making a 3D copy of pretty much what ever you want.

Plastic vacuum formers are usually big, expensive machines; however we don't always need to make huge pieces for our projects, so these machines would be pointless to have, or at least that's what I tell myself so I won't want one ;)

Our molder will have a good size for most projects that you probably deal with. If you get confused or just want to see what I am talking about, watch this short clip showing the video of a vacuum form I made.

Step 1: Gather the Pieces

The main parts to this machine are:

-A top; which is the place that the object to be copied is put and the magic happens. This has holes drilled in it so the suction is about the same over the whole surface.

-A hollow cavity, like a strong, airtight box. This is to get the same approximate suction on all parts of the top

-A vacuum cleaner (shop vacs are a pretty good choice because they have a lot of suction, but a normal vacuum cleaner will work too.) This is the source of the suction.

-Two frames to hold sheets of plastic. This can be two picture frames, or something made of Popsicle sticks.

The first plastic molder I made was a test run of what I wanted, but it worked so great, that I usually use it for all the small parts I make. I will first tell you how to make one of these, you don't have to build it, but it will show the concepts of how and why the machine works. The bigger machine is described later in this article.

Parts list for very small plastic molder:

1 - Plastic peanut butter jar or similar. (Don't use glass, you'll need to cut it some.)

1 -2 liter coke bottle or similar.

1 - Home vacuum cleaner, or similar.

A few sheets of saran wrap.

Some good tape, like electrical tape or duct tape.

Tools needed:

-- A good sharp cutting knife or razor (be careful don't cut yourself!)

--An electric drill with a small drill bit, a Dremel works nice with the standard 1/8 inch drill bit.

Ok, got it all? Let's start.

Step 2: Start Building

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First, drill a bunch of little holes in the lid of the jar, spaced about 1/4 of an inch apart. Try to evenly space them in a grid pattern. This will become our "workspace."

Step 3: Prepare the Jar

Picture of Prepare the Jar

Second, cut a hole in the side of the peanut butter jar just large enough that little more than the tip of the 2 liter bottle top will fit through it.

Step 4: Adding the "port"

Picture of Adding the "port"

Then use the knife to cut the top off of the coke bottle, Put the top of the bottle through the hole in the jar from the inside like this:

Step 5: Make It Air Tight

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Now saran wrap and tape the whole assembly. (Make sure to get saran wrap in the threads of the screw top of the jar.)

Step 6: Put a Lid on It!

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Put the lid back on the jar. The whole thing should be air tight except for the holes in the top. For plastic, I use the sides of one-gallon water jugs or milk jugs. Cut off the sides of the jugs and clamp them (or hold them somehow) between the two frames.

Step 7: Use It

Picture of Use It

Select what ever object you want to copy. Some tips on selecting objects:

-- Make sure that the object is not tapered on the bottom. This will make it impossible to get out of the plastic shell we are making.

-- Make sure that the entire object fits on the workspace leaving plenty of holes around the edges.

--Make sure the object can stand the pressure and heat of the process, otherwise they will deform or melt.

--Make sure the object is not too tall, if it is too tall, the plastic will be stretched too much, and become too thin to work with.

--Make sure there isn't too much detail on the object.

I chose the body of a tiny RC car.

Now place the selected object onto the workspace and put a spacer under the object so that the final product will look better. Use the vacuum cleaner's attachment hose to connect the vacuum cleaner to the 2 liter bottle top on the vacuum former. Heat up the plastic between the frames with a heat gun or hold the plastic over the burner of an electric oven until the plastic starts to get gooey and sag in the middle. HDPE plastic will turn from white to clear when its warm, this is normal. DO NOT use a gas burner; it will catch the plastic on fire which is not good.

Step 8: Stetch It Over the Part

Picture of Stetch It Over the Part

Once the plastic is good and saggy, slowly place it over the object. The plastic will stretch over the object. Try to get a good seal all around the object, it should be air tight to get maximum suction. Once the airtight seal is formed, turn on the vacuum. Don't keep it on, just hit it with a good second-long burst.

Step 9: Done With Molding

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The plastic will suck tight to the object and the workspace. If when you turn off the vacuum cleaner, the plastic is still gooey enough to try to come up slightly, hit it again with another burst from the vacuum cleaner. It should be done by that point. Hold it steady as the plastic totally hardens. When it is done, leave it alone for a little while so the plastic can cool off.

Once the plastic is cooled, take the frames off the plastic. It should look something like this:

Step 10: Clean Up the Edges

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Cut the extra off and put it in the recycling bin and you are done!

Step 11: Building Bigger...

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Get some more practice with it; see what you can do and how it all works.

If you would like to make a bigger vacuum forming machine, you will need the following:

--One 5 gallon plastic trash can with an approximately 8x12 inch rectangular top.

--One 8x12 inch metal baking pan

--One or two tubes of silicon caulk.

--One 20 ounce coke bottle or similar.

--Two picture frames about 8x10 inches.

Do basically the same thing as above on a larger scale. Drill a grid pattern of small holes in the baking sheet. Cut the bottom off the 20 ounce coke bottle. Cut a hole just large enough for the 20 ounce bottle near the bottom of the trash can. (Now here's where I have had a bit of a problem, you may need to reinforce or brace the inside of the trash can and/or the bottle with some wood or something before you go on, otherwise, it'll collapse under the vacuum some. It hasn't caused too many problems for me, but it could for you.)

Put the 20 ounce bottle in the hole in the trash can and caulk the seal between them pretty strongly to make sure that it is air tight. Then turn the baking sheet up side down and caulk it to the trash can. Let dry, and you are done.

Step 12: Closing Thoughts

Large plastic sheets are available online from many suppliers. Check out the United States Plastic Corp. for material, or be creative and use things around the house. If you find anything good to use that's freely available, please add a comment for others to use in their projects.

When you are finished with the plastic mold, you can fill it with either fiberglass resin or Alumilite to get an exact copy of your original object.


BraisedDuck (author)2011-02-04

QUESTION!! is it possible to use plexigless as the plastic!?

NourG (author)BraisedDuck2016-05-20

i thin it works too, it has the same properties

DavidA112 (author)2015-09-16

I am pretty sure that most RC card bodies are made of lexan.

wiz_ard (author)2015-02-26

hey well i lack experience and i have no ide what ican do with a finished prototype

please help thankyou

wiz_ard (author)2015-02-23

yeah this is really cool

but i lack experience so i have no clue what i can do with the finished product

please help me out.

robbert229 (author)2012-08-14

Very good project, just finished making it today. Soon I will have my own homemade Warhammer 40k miniatures thanks to you! Whats the best way to make the frame? I am running into some slight trouble with my frame not working very well.

jstargell (author)2011-12-10

lol i know im a lil late, but you can also make an exact copy of ur mold by reverse molding it, by sitting the mold of the object upside down and molding the inside of that mold

Valpara (author)2011-11-12

I'm not sure if this is the correct plastic, but what about the thin cutting sheets used for chopping veggies and such? It seems like the perfect size. Obviously, you can buy the clear/opaque ones, but there's also different colors, which might be beneficial to some prototypes.

I don't what they use to add the coloring... not sure if it would cause any problems. Anyways, just a suggestion because they're cheap and easy to find. The attached image shows what I'm referring too. They're 0.2" thick: 1. Flexible Cutting Board 2 Pack (12" x 18") - $3.99 on webstaurantstore.
2. MIU Flexible Cutting Board, Set of 5 (11"x15") - $9.99 on Amazon.

I was also thinking of laminating sheets, but I think they'd be too thin and stretch to the point of tearing. I'll let you know the results I get if I try either of them. Great Instructions though, thanks!

mechcem (author)Valpara2011-11-30

Type 6 plastic is the most effective and stable medium for this. Others probably could work, you should just be careful and look up there melting points and toxin release rate for them

SorinRayne (author)2008-03-05

how did you get the car out of the mold w/o deforming the mold?

sheekgeek (author)SorinRayne2008-03-05

You have to make sure you pick something to mold that has sloping sides. IN this case, the little side mirrors on the car gave me problems, but I fiddled with it until they came out. Usually a shape with sides sloping 5 degrees or more work pretty good. If you have to reform the mold, I usually just pop it back out when I am finished, or heat it up just a bit after I remove the original. That helps is somewhat. Maybe others have better tips. Hope this helps!

freerunnin1 (author)sheekgeek2010-10-15

couldn't you use any object the right size but score seams and break it, then fill with glue and wait till it sets in both halves, then stick them together when they are nearly dried, it will become nearly solid :P (about a month drying time tho :C lol)

kriogenic (author)2010-10-15

Wow, thanks for this instructable, I didn't realize the concept of these was so simple. I made the small one and it worked a treat. I then made one out of an old oven emptied out welded airtight with the glass replaced with plexiglass. as the vacuum source, a garden blower\vacuum, I made a frame for this to go on top with clamps.

to make things a little easier for the heat source, I got one of those portable bbq stoves. I then hung it upside down above my frame unit and fixed a sheet of aluminium just below that with a 2cm gap from the stove and a 2mm space from where my clips and frame is.

Finally clamp my sheet up top, turn on heat source. heats up aluminium and with the small gap it heats up most of the plastic.

and your good to go, I've made things up to 70cmW x 70cmL x 30cmH with this setup... though the oven could be replaced with anything its all i had and i had the welder rented the day before for something else anyway.

sheekgeek (author)kriogenic2010-10-15

Wow! Glad to see that this project inspired you to not only build one, but to go further with the idea. Great job! post some pics or an instructable if you can, I'm sure people would be interested in seeing your device.

tzq33tdq (author)2010-09-08

i like making stuff and this will most likely save me time/money.

batman96 (author)2010-09-06

I made a tiny one from a soda bottle cap and used milk jug plastic, it worked great! I just held the plastic to a wood frame with office clips then heated it 2 inches above a candle, just move in a circular motion don't let sit in one place, when the plastic turns clear you are good to go.

paqrat (author)2010-09-04

Thanks for a great instructable. Many years ago there was a "toy" vac-u-form, I believe made by Marx. I had one and played around with it. I think I will definitely be making one of these. I think this could be most useful (and inexpensive) to make molds from which one could make wax models for lost wax casting.

paqrat (author)2010-09-04

I wonder if using a cylindrical trash can instead of the rectangular one might make it less likely to be deformed by the vacuum? Seems like the large flat sides would make the rectangular trash can more vulnerable.

chrisnbolen (author)2010-08-08

just wanted to thank you for posting this instructable, I used totally different materials (only things I had on hand without spending anything) and man does it look good. I plan on using old DVD cases to form around my cell phone to make a custom holster for it, then who knows I've a good imagination. I also added a one way valve using thin sheet plastic so once the vacuum is created it will hold till the work peice is removed. it's still drying so I haven't tested it yet. Cheers Chris

rcamp004 (author)2010-08-01

The best place for all kinds of parts is McMaster-Carr. My engineering buddies told me about this place and it always has everything you could need for any project (that I've run across). HDPE link to McMaster-Carr I don't work for these people, It's just every time I've hit a materials roadblock this company would get me out of that rut. Hope this helps any other builders out there short for materials.

InventiDan (author)2010-06-18

Go to Lowes, Home Depot or any Hardware and get Acrylic sheets. They are sold anywhere PlexiGlass is sold. IE: Storm doors and windows. There is acrylic and poly.... something sheets. sorry I forget the exact name of the poly sheets, But I have used the Acrylic sheets and they work great and are sold in many different thickness. So if you have something tall to do, you wont strech it too thin. And as for heating it, Use your oven set for 350 to 400 for 3 to 4 minutes. Hope this helps.

IcedZ (author)InventiDan2010-06-21


thalden (author)2010-06-18

The lining on the boxes that cooking grease comes in are HDPE. Ask your local restaurant if they can save you one. You get about a foot and a half square of flat plastic off each side, if not more.

spudstud (author)2010-05-23

 This is very helpful.  I am having a hard time finding the plastic sheets you refer to. Could you post a link?

kitten55 (author)2010-05-19

This looks easy to make. But with it being finished, how do i use it? like, how does it suck?...or is just a replica or an actual working vacumm.

XOIIO (author)2010-04-25

How did you make the popsicle frame so that it was even?

sheekgeek (author)XOIIO2010-04-26

I made something like a  "rabbit" joint at the ends of the large popsicle sticks so that they fit together evenly. Then reinforced the corners by gluing smaller popsicle sticks across the corners, but only on one side. This left the other side flat. Making two of these allows you to clamp plastic between the two flat sides.

You can use any kind of frame for this though, Dollar store picture frames are another idea I had.

Goog luck!

XOIIO (author)sheekgeek2010-04-26

Sweet, thanks! I plan n making this, then the garbage can sized one and ordering sheets online, then once I learn to weld I will make one like MythBusters did.

duck_tape_ (author)2010-04-25

Would using screen (like for a screen door) work?

Fizzxwizz (author)2010-04-24

Here is a good list of HDPE products

Bostonians (author)2009-07-28

I do not have a heat gun nor an electric stove burner. Does anyone else have any recommendations for heating the plastic? Great instructable

Late reply, but it might help someone.  Years ago, I was building a replica of a sci-fi robot and needed a clear curved/bubble faceplate.  I put a piece of plexiglas over an old electric space heater set on low and it worked great.  I didn't have a mold; I just softened it and then held it horizontal and let it droop a bit, and repeated the process until it was the shape I wanted.


sheekgeek (author)Bostonians2009-07-29

You really need an electric heat source. Anything with an open flame will melt the plastic and make it useless. You can attempt to use a hair drier, but I really don't think that'll work well. You are better off buying a heat gun. They are pretty useful if you do other projects and crafts.

itsthatsguy (author)sheekgeek2009-10-03

I used a blow torch, i used the highest flamer size and waved it rapidly over a 6x6" plastic sheet, the plastic was thicker than most vacuum forms s that probably why it worked, But if you move the heat enough it won't burn a hoel through it.

Lance Mt. (author)2010-01-21

 Question. Milk bottles are used in a food context so if you cleaned said milk bottle plastic THOUGHLY after melting/shaping would it still be food grade?

Cheers, feel like making a huge one.

1tri2god (author)Lance Mt.2010-04-23

Food grade is an measurement of sterility of the manufacturing and shaping process as well as lack of impurities in the actual content of the container itself.  So in theory, as long as the milk carton was THOROUGHLY cleaned, as well as your vacuum forming device, you'd be pretty close to the spirit of the description.  I can't speak to the measure of off-gassing that plastics do when heated, though (as you'll note that milk containers use a different plastic than, say, the ones intentionally designed for use in the microwave).  Hope that helps!  All around, a great instructable to get novices into the art of vacu-forming!

Lance Mt. (author)1tri2god2010-04-23

 Thanks.. I'll see how it turns out before I start a cancerous pet-project.

stupidstickanimations (author)2010-04-23

ive been wanting to do something like this for a lego gummie instructable :D

kudoskun (author)2007-02-27

Instead of the coke bottle...couldnt you use a vacuum attachment for easier hook up? Probably one of the lesser / if ever used ones.

servion (author)kudoskun2010-03-22

thats right. and you avoir collapsing problems with the bottle...

Lance Mt. (author)2010-01-21

 Hot water. And alternate to heat gun for those cheap like me.

Skye-hook (author)Lance Mt.2010-02-02

There is also a  much easier way! Though this way sounds fun.
ShapeLock plastic pellets you melt with hot water only can be used easily for most things like this, however- you need to have it definitely ON the item you want to copy or add to before melting with hot water,. Otherwise, working with it after will leave you with bumpy products you must try harder to make look good. So there are times you'd probably want to use a thin plastic sheet instead. Many things can be done with though, & it's strong.  Can also be used for emergencies. I love it.             * See       Gotta try this way on Instructables though, sounds really fun!

scarabeetle101 (author)2009-12-15

 Would the plastic sheets used in laminators work?

kewlkiwi (author)scarabeetle1012009-12-21

"Would the plastic sheets used in laminators work?"
Probably not advisable, since they contains 2 (or more) layers of different plastics with different melting points.

The inner layer melts at a much lower temperature than the outer, so that the inner layer sticks to the paper being laminated, while the outer layer is unaffected by the heat.

gelicab (author)2009-07-05

I need to make 2 plastic cylendars kind of like ink pen style. Where ifyou turn one the pin will come down. Does anyone have an idea of how to do that? Thanks

scarabeetle101 (author)gelicab2009-12-14

 Why don't you try just replacing the ink thingy with a needle?

itsthatsguy (author)2009-10-03

I built one using a massive shop vac, it works really well, preliminary tests showed i need a better way of heating plastic... might make a Plastic "Furnace"-- aside from that it works very well. made a few plastic models of electronic components (Capacitor-rectifier-Quarts crystal)

katita (author)2009-07-28

thank you very much for your free site...i really hope this helps me creat a prototype for my question is i am looking for a soft non degradable plastic for medical ..use... or where i can go or see plastic samples..use. thanks again

sheekgeek (author)katita2009-07-29

I'm really not sure where you can find medical grade plastic. The best idea I can think of is to make some prototypes yourself to get the shapes the way you want, then go to a company that will help you with manufacturing such as Enventys. or IDEO They have the experience required to help design, fabricate, and manufacture medical devices that can be implantable.

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