vacuum/molding material question?


Sr Member
Question:At work we vacuum form for mock-ups in packaging. Say we need a to make a block , well make it out of thin cardboard, and then use thin sheet metal over it to form a block. Is there something easier say some type of clay where we use the measurements and just cut out a block of it? Only thing is we use clear plastic, so it cant leave any residue or film on the clear plastic. thankyou any info. :)

division 6

Master Member

At the Aqurium manufacturer I used to work at we vacced tank cover plates over acylic bucks.

Masonite will stick to what ever type of plastic you are using.
The table bed was made of the stuff and it had to be replaced every few months.

Hard woods work well also.
Our light fixture boxes where formed over hard wood and acrylic bucks.
The acrylic bottom pieces sat on small nails and could be popped out once vacced, since they formed an undecut for the face plates to sit in.



Well-Known Member
My local group has been using modelling foam for the initial bucks... though we then make cement casts after the first pull, because the foam does not handle repeated pulls all that well. You can find it here, among other places:

I had thought that clear plastic had to be injection molded, and that vacuum forming it would make it cloud up. What kind of plastic are you guys using? I've got a costume project I've been putting off because it really needs large clear plastic portions with molded details.


Well-Known Member
<div class='quotetop'>(takevin @ Jun 13 2006, 06:06 PM) [snapback]1261130[/snapback]</div>
pet-J plastic , is the modeling foam easy to sand? thankyou Kevin
I've not done much with it myself (I'm a terrible sculptor), but I've seen some very impressive work done with it, and it seems to cut and sand very easily. There are different 'grains' of it available, and the finest grain stuff gets a bit more expensive, obviously, but I'd think it would do the trick if the others didn't. I've only seen it used on thick, opaque plastics, so for a thinner, clear plastic so I'm not sure what grade of foam you would need, but it sounds like it would be a good solution to the problems you listed.


Well-Known Member
I did my trooper armor molds in MDF. Its a type of plywood, that once sanded, leaves a nice smooth finish. Seal it with some primer paint and you are good to go. Bondo is almost the same hardness, and a glaze of that on the surface works great. There use to be a great thread about vacuum forming but it has gone away now. :( But I have started a discussion board on this very subject: