My mold frames are made from 3/4" thick laminated shelving material and are reusable. I attach my patterns to the mold bases with double-sided paper tape. I use both 2" and 3/4" widths. For open-face molds I not only don't bother cutting the paper tape to the outline of the part, I completely cover the mold base with it. The adhesive doesn't inhibit the cure of the silicone rubber, and the surface of the resulting mold is even with the back side of your part so the flash is thinner. That's for tin catalyzed (condensation cure) silicones. For platinum catalyzed (reaction cure) silicones it probably will inhibit the cure.
