Tablet touchscreen sensor? (No-LCD)

I’m trying to replicate the feedback / PID mechanic from this project (Ball and Plate PID control with 6 DOF Stewart platform - YouTube ), and I’m looking for a touchscreen sensor (similar to an iPad touch screen) that doesn’t have any LCD. I just need a sort of giant trackpad, ideally that can provide multi-touch X/Y coordinates of some sort, preferably over an I2C interface.

Has anyone heard of such a thing? I’m looking for something that is NOT attached to an LCD screen in any way.

thanks!

EDIT: Doesn’t have to be Capacitive. Could be resistive. Also doesn’t have to be I2C, could be 4-wire.