Build your own drum pad
With the Drum kit – Kit AI by Spikenzielabs you can build an electronic drum kit. The bundle contains all of the electronics, including the piezo sensors for the drum pads. You build the drum pads yourself, and then connect the Drum Kit – Kit AI to your computer to play sounds using your favorite audio software, or use the MIDI-out port to a connected drum synthesizer.
Roberto De Nicolò (aka Rodenic) has realized an useful tutorial video showing what he has called FingerDrum. Roberto has applied a piezo sensor to each finger of a glove, allowing the triggering of individual drum sounds from his midi expander. If you think the glove is unconfortable, check out the FingerPad and turn your mouse pad into a drum pad.