Material question

Hey wassup ya’ll…I’m trying to form a model about the size of a back pack to vaccum form. Does any one know which material is cheapest and easiest to use? Like clay, or foam…but those can get heavy, expensive…Does anyone have any suggestions?


There’s alot of methods. For a light mold, you could use a light density styrene foam (blue foam). Then seal it with paint. I don’t think the vacuum pressure is enough to deform it, and with vacuum forming you don’t normally pick up the small irregularities that a styrofoam mold will have. It’s cheap too.

Another option would be to use sheets of balsa wood. Depending on the shape of your mold, you could use sheets as thin as 3/4". If you plan your mold out well, that shouldn’t break the bank either. Plus a wood mold will last longer if you need to repeat your part.

You mention clay. I have seen clay molds before, but I would stay away from it unless your mold needs to have very organic shapes. Otherwise, I don’t see an advantage to clay.

you mentioned foam and clay being too heavy, if that’s an issue, it might be tough to find a solution that meets all your requirements.

If weight isn’t a huge issue, you can use plaster for the rough cavity and make the cavity out with yellow or blue/pink foam. That won’t be the lightest solution, but it will be strong. And give you the possibility of a really nice finish.