No confidently-playable version exists yet for these — here's why, and what's closest.
Bassoon
Open · hard mode
Double reed plus a long folded conical bore — build volume and bore accuracy at once.
Closest: Nothing playable. Contrabass recorders show folded-bore printing is at least feasible.
Sectioned print + real bocal + reed. A genuine 'first ever' if it plays.
Euphonium / baritone
Open · mouthpiece only
Valved conical low brass — same airtight-valve problem as trumpet, bigger.
Closest: Mouthpieces only. The PrintBone slide trick doesn't transfer — these are valved.
If the trumpet valves get solved on camera, this is the scale-up follow-on.
French horn
Open · mouthpiece only
~12 ft of tightly coiled conical tubing + rotary valves, all needing to stay airtight.
Closest: Playable printed French horn mouthpieces ($5). No full instrument.
Hardest brass. A single-Bb, valveless 'hunting horn' variant is the realistic first step.
Kid-size cello
Queued · fastest win
String tension doesn't scale linearly — shorten the length, re-check the rod gauge.
Closest: The O'Cello — a proven, playable full-size base to shrink.
The original request. Scale-and-reinforce, not from scratch. First 'Verified' entry candidate.
Oboe / English horn
Open · ancestor exists
Double reed + precise conical bore. Tiny bore errors kill intonation.
Closest: A printed musette / shawm (the Renaissance oboe ancestor) that plays on a real oboe reed.
Bridge the gap: print the shawm first, show why the modern oboe's conic bore + keys are the wall.
Saxophone (home FDM)
Open · proven on SLS only
Dozens of interacting keys and airtight pads over a conical bore.
Closest: Olaf Diegel's alto sax — printed, playable, but SLS nylon on an industrial machine, not a home-FDM download.
The prize: a home-printable alto. Even body-only + salvaged keys (JDWoodwinds' clarinet approach) would be a landmark.
Timpani
Open · hybrid at best
Large tunable kettle, real drumhead, and pedal tuning mechanism.
Closest: Printed rims/lugs and small hand-drum shells; no full pedal timpani.
Realistic target: a small hand-tuned kettle drum, not the pedal beast.
Tuba / sousaphone
Open · sectioned build
Enormous (build-volume problem) plus valves.
Closest: Decorative models and mouthpieces. No playable build.
Print in sections + real valve springs. Even a playable-ish one would be huge content.
Verified playable trumpet
Flagged · flagship verify
Candidates exist but none confirmed by an outside build.
Closest: The Full Size Working Trumpet (Selmer-based, in the registry).
Build it with real springs + felts, play it on camera. Instantly the most valuable entry in the index.