Step 2: Assemble Mold

Assemble Top Mold

Glue the central block to a sheet of cardboard and trace the bottom with hot glue to prevent rubber from flowing underneath.
Build the surrounding wall around the central block, with a 0.25” gap between the block and the corresponding side walls and a 0.5” gap between the short sides of the block and the end walls.
To prevent the mold from leaking, seal all joints with hot glue. This should be done at least twice to ensure there are no leaks.

Assemble Bottom Mold

Make the bottom mold by tracing a 7” by 1.5” block with hot glue. After the glue cools trace the box again to add a second layer of hot glue. Repeat until the hot glue is stacked about a 0.25” high.

This is what the mold looks like when completed. (The paper is used in the fabrication of the actuator.)