echoPi build logs

Notes from building echoPi, a pocket slider that plays the next note of a song with every push.

• echoPi build log #1 — the detent: a steel ball, two springs, a 3.33 mm pitch 2026-11-08
• echoPi build log #2 — one push, next note: 5 rules we set before placing a single part 2026-11-07