During testing of the instrument, I found a few things to improve:

1, I used Kanthal wire for strings. This wire is great for wire-wound resistors (that's why I had a lot of the wire in my workshop), but it is a bit tarnished on the surface, causing both unclear intonation of the instrument and stained fingers of the player. I ordered nichrome wire, should be better for this task.

2, The fingerboard is too wide. I need to make it thinner and possibly curved.

3, The curvature of sensor head is not enough and occasional unwanted neighboring string is bowed. A tiny bit more of curvature should do the trick.

4, Playing with sound. While not completely bad, it can be improved. I thought of adding a few coupled resonance filters after mixer (uhm, schematics will make it clear) to make the sound more live.

5, I setup the magnetic sensors (sensing bow speed) according to my non-cellist style. Real cellists are playing with more energy, so the instrument is lacking rather huge part of dynamic range. Playing with resistors in voltage control mixer should do the job.

6, MIDI output? Should be doable.

7, I need to see real cello one day. Really, I never held this instrument in my hands. From this perspective, decision to start making cello may sound a tiny bit silly. Let's call it exploring new horizons instead.