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

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

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"

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

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!

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

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

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

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

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

Step 11: Building Bigger...

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.

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    205 Discussions


    Reply 3 years ago

    i thin it works too, it has the same properties


    3 years ago on Introduction

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


    4 years ago on Step 11

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

    please help thankyou


    4 years ago on Introduction

    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.


    6 years ago on Introduction

    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.


    7 years ago on Introduction

    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


    7 years ago on Step 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!

    Cutting Board 2.jpgCutting Sheets.jpg
    1 reply

    Reply 7 years ago on Introduction

    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


    Reply 11 years ago on Step 9

    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!


    Reply 8 years ago on Step 9

    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)


    8 years ago on Introduction

    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.

    1 reply

    Reply 8 years ago on Introduction

    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.


    8 years ago on Introduction

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


    8 years ago on Introduction

    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.


    8 years ago on Step 11

    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.


    8 years ago on Step 11

    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.


    8 years ago on Introduction

    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


    8 years ago on Introduction

    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.