Experienced with casting concrete in silicone molds. I am looking to vacuum form some castles similar to the Elastolin castles made in Germany in the 1960s-1970s. They seem to push the process to the limit. Anyway, is there some kind of silicone or other flexible mold tooling that could be used for more complex designs for vacuum forming? I plan on using negative molds with a fairly thick plastic (1/8" or greater). I know it would work but mold life may be too short. Would like to produce 200 or so before the mold wears out. Also, anyone have success with using concrete molds?