great, thank you all for you ideas. i will have to figure out now if I want some really sophisticated solution with with a lot of coding and stuff or just to try to make it as simple as possible. conductive paint would definately be a pretty simple and convenient solution. but If it is possible to create a whole metal sculpture out of a square (or rectangular) base surface, capacitive sensoring would probably be possible. (it would be like a folded touchscreen). it is also a very "organic" way of sensoring, considering that the nervous system also works with electrical impulses & fields.