The basic design I'm going with for the vacuum plate/box is a small box, with a shopvac connector on the bottom, pegboard as the top, screwed together, and metal foil taped to seal air gaps. This is sort of a mixture of a few different designs I've found on the net. The material will go on its own frame, heated by a heat gun, then pushed down onto the vacuum frame, with the shop vac turned on. The softened material will get sucked in tight against the mold, forming it into that shape.
Next comes the foil tape to seal it up. Finally some door weather stripping to act as a good seal with the material frame.
So... How did it work?
Not great. It was ridiculously difficult to get the material heated consistently and hot enough. The heat gun would burn a hole through the material if left in one place, but the material cooled off too quickly if you moved away from it for too long. I need to build a heater rig to prepare the material.
One thing I wasn't expecting was the odor of the plastic, especially this green plastic seen above. MAN, does it smell horrible. When you see people mentioning "work in a well ventilated area" they aren't kidding. The plastic continued to have a foul odor for a few hours after it cooled down. I had to drive home from Interlock with my windows down.
It shows promise, but it's not quite there yet. I wouldn't call it a success, but I wouldn't call it a failure either.
Note: This post was originally posted to the Interlock project blog.