Touch contacts, body points, and galvanic sensors are all names given by the DIY community to these Cap Nuts! Often seen on circuit bent devices and some DIY synths they are quite elegant. Basically they are regular nuts with a metal dome. The back of the package features bolt sizes that will work with a particular set. It is critical to pick the right length for the case thickness because of the obvious limitations posed by the capped off nut. However washers can be used to solve the issue. The wire from a particular point on the circuit board can be threaded through the bolt with a use of a ring terminal. This package cost me $0.89, but some can get expensive. Any decent hardware store should have them, but finding these amongst all the other parts can be tricky. So ask for them by name, loud and clear. “Pardon me, but do you know where I can find some Cap Nuts?”