Card-sized 3D-printed whistles. Swap a card, change the key.
日本語版は README.ja.md をご覧ください。
Eight fipple pipes are 3D-printed into a credit-card-sized plate (85.6 × 54 × 4 mm).
- Chordika — blow any three adjacent pipes in one breath and a tuned triad sounds. Twelve cards cover every key, and the position-to-chord mapping is identical on all of them, so the same hand motion transposes when you swap the card.
- Recorika — the scale counterpart: one octave of a major scale, lowest pipe on the left, highest on the right.
The data is published, so anyone with a 3D printer can make the same thing. Each card is exactly credit-card sized, so it travels in a wallet or a card case.
Project site: https://unryu.org/chordika/
On every Chordika card, the same pipes give the same chord function:
| Pipes | 1·2·3 | 2·3·4 | 3·4·5 | 4·5·6 | 5·6·7 | 6·7·8 |
|---|---|---|---|---|---|---|
| Chord | ii | IV | vi | I | iii | V |
| on C / Am | Dm | F | Am | C | Em | G |
| on G / Em | Am | C | Em | G | Bm | D |
Each card therefore carries a major key and its relative minor. Only vii° (the diminished triad) is missing.
This works because the notes are ordered by scale degree 2·4·6·1·3·5·7·2 rather than by pitch — which makes every three adjacent pipes a diatonic triad.
index.html project site (Japanese / English)
stl/ print data — 12 Chordika cards, 1 Recorika card, 1 cover, 2 box parts
3mf/ pre-sliced files for the Bambu Lab A1 mini (PLA), the same 16 items
video/ short clips of the cards being played
assets/ cheat sheets (JA/EN), chord maps for all 12 keys, photos and figures
Hear them: start with the demo video on YouTube. The project site also has short clips — chords on Chordika, the scale on Recorika, and a tune played on it.
If you own a Bambu Lab A1 mini, the files in 3mf/ are already sliced with the
settings below and can be sent straight to the printer. They assume Bambu PLA Basic;
each card is about 8.5 g and takes roughly 1 h 15 min. For any other printer or
filament, slice the STL yourself using the settings below.
- 0.08 mm layers, 0.5 mm outer wall. The pipe walls are thin; do not print coarse.
- No supports. Print flat, as-is.
- One card per plate. Two cards on one plate double the time per layer, the edges cool and shrink, and the card warps. A brim alone will not stop it.
- Brim about 5 mm, brim-to-object gap 0. With a gap the brim never fuses to the part and holds nothing.
- White PLA works well. Translucent PETG is beautiful — the bores show through the plate.
Blow with about as much breath as a recorder. Too hard and the pipe jumps an octave.
The cover (chordika_cover.stl) is a 0.5 mm plate with no pipes and "Chordika" cut
through it. It shares the cards' outline and strap-hole position, so it stacks on top of
the twelve and threads onto the same cord.
The box is two parts: an open tray (chordika_box_base.stl) and a lid that slips over
its outside (chordika_box_lid.stl). All thirteen cards lie flat inside, and the lid
carries the same cut-through lettering as the cover. A scallop on each long side lets you
pinch a card out. Closed, it is about 94 × 62 × 57 mm.
The box holds no pipes, so it prints at ordinary 0.2 mm layers with no supports — no need for the fine settings the cards require.
Pipe length and pitch were fitted from real printed-and-blown pipes as f = A/(L+e).
Solving it backwards turns a wanted note into a length, so a generator written in Python
(trimesh + manifold3d) emits the whole card from a key name. The plate thickness is fixed
at 0.5 mm — exactly the floor thickness of the pipes; any thicker and it eats into the
bore and the card goes silent.
CC BY-NC-ND 4.0 — see LICENSE.
You may print these for your own use, play them, and share them unchanged with credit, including non-commercially in classes and workshops. You may not use them commercially (selling prints, paid services) or distribute modified data. If you want different terms, please get in touch.
From the "AI whistle-making" project by Kazutaka Kurihara (Tsuda University).