What sensors for a MATERIAL TOUCH/FEEL device?

A record player uses a piezo crystal on the needle to convert the roughness (?) of the record into an electric signal. Along those lines you could probably solder a pin/nail/etc to a piezo disc and emulate a record player -- or just use a record player needle of course. The signal out from the piezo would be varying frequency and amplitude and there will still be a requirement for tons of amplification/massaging of the signal.