Update, 2024-05-13: Mouthpiece added (v3) for great bass bore v4.

THIS IS A WORK IN PROGRESS. The instrument as published is not ready for performance. I'll remove this once the posted files result in a printable, playable, and in-tune instrument.

This is my printable take on the baroque greatbass recorder. The low register recorders designed by Joachim Petzold in the 1970's were a strong inspiration. It seems that recorders may have been relegated to period music or institutional education by that time. And low register recorders had always been rare because they were expensive to produce and had a very limited pool of users. Paetzold's plywood recorders defied conventions and assumptions about woodwind instrument design, materials, and their associated potential impacts on sound. The result was louder, deeper, and more economical instruments than had been previously available to recorder players. And these new instruments with their new capabilities, new aesthetic, and relatively low cost inspired a renaissance in recorder composition and performance.

Further, Yamaha's Venova instruments, invented by Hideyuki Masada and Yuechiro Suenaga, incorporated a number of novel features that leverage modern manufacturing capabilities: a wandering bore brought vents close together and a branched-pipe bore allowed the majority of the bore to remain cylindrical and retaining a small diameter. These two innovations allowed for a compact instrument with rich harmonic content, almost no keywork, and two octaves of range.

To the instrument at hand: A greatbass recorder has a range that starts at C3 (C below middle C on a piano, or 131 Hz). Normally they have a mostly straight bore that's about 48" (1.3 m) long. This results in vents spaced too far for unassisted finger reach. Early recorders accommodated for this with metal keys. Paetzold constructed keywork from flat plywood plates.

Bore orientation and smooth bends generally have little impact on sound. For this reason, bore paths have generally been chosen for convenient construction. For woodwinds, where the bore is often turned from wood, straight bores (supplemented with metal bends, if required) have usually been the practical choice. For brass instruments, the challenge instead has been the long and multiple bores required and the medium of choice (soft metal tubes) lent itself to bending.

For 3D printing, the primary constraints are print volume and material properties. The most affordable FDM printing materials are reasonably stiff, but still far less so than wood or metal. To produce practical instruments in these constraints, I've been bending the bore arbitrarily to fit within the print volume and to bring vent holes within finger-reach. Having vent holes much smaller than the bore along with the geometric complexity of searching for an appropriate bore path have driven me to employ SW design tools. Python, INRIA's OpenWind module, Octave, and OpenSCAD are a few of the excellent open source tools that I've used in this process. My working branch of OpenWIND with my instrument design scripts are here:
https://github.com/thecowgoesmoo/openwind

Here's an early demo:
https://youtube.com/shorts/KscgOls1iFU?si=6Jagh9ki3IRWUvz9