There are hardly any instructables on this subject, and none with this design. It's an original idea by my dad and I. We were going for as cheap as we could go, while still making a product we wouldn't be embarrassed to use in public.
We built a full set of electronic drum pads, which I'll explain here, and also a low-cost PVC rack for the drums, which I'll post a separate "how-to" on.
Step 1: Materials
For each drum pad, you will need:
1x - 3/4 inch plywood, 8 inch diameter circle
2x - 1/4 inch foam of some sort, from mousepad or floor-mat...(more on this later), 8 inch diameter circle
1x - sheet metal, preferably of some light or medium guage, 8 inch diameter circle
1x- smaller square of sheet metal, about 2x2 inches
1x- peizo-electric element, 35mm is better, but 27mm or something will work
1x- heavy fabric, i used a material called "trigger" that's used for work uniforms, circle with at least 14 inch diameter
1x- vinyl material, 8 inch diameter circle
1x- RCA style audio jack
1x- plumbing bracket with 3/8 female threading, normally used for attaching pipe-hangers to surfaces