Thread: Drum Pad to Eurorack?
Starting point #1: https://www.sweetwater.com/c644--Drum_Triggers_and_Pads
That's pretty much everything you can commonly get in the marketplace these days when it comes to electronic drum pads, sensors, and the like. The other starting point would be to pull up the 'Drum' listings on here (preferably in Eurorack, which has the most options) and look for modules which feature a drum-trigger input OR modules which can translate a drum trigger into a synth gate/trigger output. Attach part 1 to slot 2, finish the synth build, pull out a pair of sticks and go nuts.
(FYI, the Markdown formatting bollixed the URL above. Insert a _ in between Drum and Triggers, and between Triggers and and, then maybe lose the italics, and you're golden.)