This soap mold will nicely hold 20 ounces of soap, which is the default size of the soaps created in this book.
Supplies:
ΒΌ-inch-thick plywood, 8 x 14 inches
Wood glue
2 clamps
A book or something a little heavy to add a some weight to the top
Method:
Cut plywood into three 7 x 4-inch pieces, and two 4 x 3.5-inch pieces. Glue the smaller pieces onto one 7 x 4 piece as shown in the image and then the sides. Place the clamps to hold the wood pieces together (see image). Set this in a safe place to dry for a day and set weights on the top to help the bottom stick.