razor blade. i, then, used ordinary white glue to hold the box' parts together. as seen in the next photo, clamps were used to hold the side pieces to the long side panels. the master was glued to the bottom of the box using white glue also. the vertical pieces are almost 1/2" taller than the master.
the next photo shows the final box. i added diagonal pieces to reduce the amount of rubber mold material needed.
years ago i had bought the mold-making kit by micro-mark. unfortunately, when i opened it to use for this project, "part a" had completely hardened. i guess that stuff has a shelf life of only 