I decided to use melamine paneling as the baseboard, as it is very smooth on one side. I drew the basic outline of the cast on it, and used a skill saw to cut it out leaving enough room to add 1x4 boards to the sides. It left about 3/4 of an inch of room around the cast. (Fig. 2)

Figure 2. Preparing the box for the mold.

I screwed the 1x4 boards to the bottom, and hot glued the corners. I then caulked the inside of the base of the box to make it liquid tight. After doing the same with Paul Freeman’s cast, I took a gallon of water, and poured it into the boxes with the casts in them to see how much silicone would be needed. Do NOT do this if you are using plaster of paris casts to duplicate. I could see that it was going to be close, but probably just shy of the needed silicone. Therefore, I took some of my Play-Doh, and filled in and rounded the inside corners of the boxes. I then filled in some of the other areas, keeping at least a half-inch of room between the Play-Doh and the cast. (Fig. 3)

Figure 3. Play-Doh in the box corners of the box

Now with the Play-Doh displacing some of the silicone, I was sure I would have enough to pour the mold. I found out later that this aided me in removing the mold, as the silicone really bonded to the wood making it necessary to cut it away with a razor blade.