This is my blog describing how I started building my own digital piano. It all began with a cheap digital piano I wasn't satisfied with and involved developing my very own piano sensor bar(as existing ones where out of my budget), which is also described in detail. Later I installed this bar at old piano actions to come closer to the ideal piano action feeling:

There is something special about this sensor system as it uses a physical model that involves calculating how the hammer shafts in a piano action bends thus simulating the exact timing of an actual (grand) piano action. All physical parameters are user customizable (per key).

NOTE: This has started and still is a private DIY project, but if a community forms it may be commercialized in the future. My ideal is to give an appropriate midifying kit for a reasonable pricing to the world, but I'm still far away from that goal, So I hope I won't break any advertising rules by my post. I'd love to support this forum by paying for an advertisement, but I'm just a student and could not afford it.