It uses strat pickups wired in series (was in parallel and hooked up with alligator clips for the original demo video, wiring was altered later, there will be an update later) for picking up the springs.

The springs were some 5" springs I got off the shelf at a local industrial surplus store. They are wrapped around duplex nails (double headed nails) at either end, and are tuned by changing the length of each element at the nail(tension only slightly changes pitch).

Demo Video Link, Odysee Mirror