Step 3: Cutting Parts
I bought a sheet of 3/4 inch plywood that perfectly fit 9 of my 8 inch circles. Draw them all out and then cut them all out at once with a jigsaw. The rough edges can just be quickly hand-sanded smooth.
We got 16 foam, 8 inch diameter circles out of the 2 foam mats. Because each pad needs 2 circles (once for under the peizo+sheet-metal layer, and one for above) this is enough for 8 drum pads. As with the wood, we just drew them all out with sharpie, then cut them out with scissors.
*For the first pad, we used 2 mouse-pads instead of the foam, but quickly realized that this would be far too expensive at 4 dollars per mouse-pad.]
For the sheet metal circles, we just rolled out the aluminum flashing, traced our circles, and used the metal snips to cut them out. If you cut them out as squares first, then trim them to circles, it makes the process a lot safer and easier. (The edges are sharp. Be Careful.)
There will be lots of left-over metal from the circles. What i did was salvage this by cutting out squares about 2x2 inches. these will be the mounts for the jacks, so they will also need a 1/4 inch hole drilled through the middle.
The vinyl can be cut into circles with a diameter of 8 inches or just under, depending on how you want your edges to look. mine are right at 8 inches, the same as almost all other parts of this design.
These circles can just be traced out, then cut with scissors.
The fabric circles will be the one element of this project that will be cut larger than 8 inches. These need to be able to wrap around the layers of wood, foam and metal, and be stapled on the underside of the plywood. A diameter of around 14 inches should give you enough to work with. This can also be traced out and carefully cut with scissors.