- Utility knife and Scissors
- Soldering iron
- hot glue gun -optional, contact spray might work better honestly
- Wire strippers and snips
- Conductance tester- Multimeter
Cut the sign board into 8 (11"/ 28cm) squares. With sign board its useful to leave extra space and trim down to the cells. In a high quality version, 4 rubber sheets and 4 Plexiglass sheets might be a good substitute.
Cut the foam into 16 small rectangles (about 1" x 2") , exact size depends on the type of foam used. Soft more, hard less, fairly soft foam is used in this pad. Hard or thick foam may make the pad difficult to use. Real pads use perforated sheets of thin (1/4") foam, this works well if thin foam sheets can be found. The redundant buttons on old pads provide good sheets. The directional key foam on store bought pads normally is the first thing to wear and lose resiliency. Making a faulty or unreliable pad. Another idea to separate the pad contacts might be short and wide springs given they are insulated from the contacts and fastened properly.
8 pieces of aluminum foil are needed to act as the pad contacts. About 70-90% of the square size is sufficient. In a higher quality version it would be nice to use sheet metal. Drilling holes for the contact wires fishing them through and soldering in place. In this case contacts will be "secured" with foil tape. It works well enough, but for how long is another question.