dany....
get little piezo discs from a electronic supply house....
shown in this link...
http://www.electronicdrums.com/pads/pads2.htm
(pivc in step 3....).....wire the piezo to a qtr inch male jack.
glue vinyl tile either side of piezo to enclose it and your done.
there are many fancier ways also.
just google diy piezo drum trigger. peace.
ps...experiment with different materials to enclose piezo like soft rummer/tile
various sorts etc. ive even made kik piezo triggers.