Positive Clay Sculpt to Positive Plaster Mold for Vacuforming


New Member
I am new here and would like some advice on making a mold for vacuforming. I have made a vacuum forming table and have a good heat source but am stumped on how to create the mold. I have very hard natural drying clay sculpts but in my research have come across no one recommending to form right over this. I have seen a lot of people use plaster to create their molds. I was wondering if anybody knew any good methods on how to take a clay sculpt, cast it with whatever material and then pour a plaster mixture into that casting. Any advice would be greatly appreciated. I have looked into Silicone 73-20 but that stuff is far out of my price range and I have no familiarity with it. The plaster I have is Plaster of Paris btw.

:) Any help will be greatly appreciated :)


Sr Member
You can try using 100% silicon (in a the tube available at a local hardware store), glycerine, acrylic color (to tint it) and try that for your silicon mold. There's some youtube vids that show what exactly you'll need for this process. I personally haven't used this method but, give it a shot as I've seen some decent results with it.

Here's one vid that outlines this process.
Last edited by a moderator:

division 6

Master Member
Sculpt with WED clay.
Let stiffen till it's leathery.
Vac over it.
Fill with Ultracal 30.
Tune up cast and you're good to go.
This thread is more than 6 years old.

Your message may be considered spam for the following reasons:

  1. Your new thread title is very short, and likely is unhelpful.
  2. Your reply is very short and likely does not add anything to the thread.
  3. Your reply is very long and likely does not add anything to the thread.
  4. It is very likely that it does not need any further discussion and thus bumping it serves no purpose.
  5. Your message is mostly quotes or spoilers.
  6. Your reply has occurred very quickly after a previous reply and likely does not add anything to the thread.
  7. This thread is locked.