It's one of those electronic music DIY dreams: building drum pads from
scratch. Sound on Sound had an article in 1995 that goes through, step
by step, how to build a drum pad and trigger system. You'll want to check out the Physical Computing
page, too. Anyone want to give this one a try? Hit comments if you
have, are planning to, or have other good resources. (Stay tuned for my
own adventures in piezo sensors.)