Ribbed Bellows (for a small pump organ)

This is a component for a pipe organ design I've been working on.  Of course, it'll also work on other applications that require small amounts of compressed air power.

Instruction videos:

Youtube playlist

Very important notes:  

1. This model requires two print profiles - one for soft TPU (0.6mm nozzle) and one for PETG (0.4mm nozzle).  I've had mixed results printing soft TPU with a 0.4mm nozzle, and don't recommend it.
2. This model requires using a 3D pen loaded with TPU to weld most of the parts together.
3. PETG is specified because it welds to TPU.  PLA welds very weakly to TPU, and will not work.  The few non-welded parts should also be PETG for matching shrinkage (e.g. if the hose ports are PLA and the valve box is PETG, they won't fit together).
4. I recommend printing 3 copies, as shown in the video below.  This takes a whole week to print, and a few evenings' work to assemble.

Specifications:

Volume per pump:  ~ 8L / 0.28 cu. ft.

Air flow rate:  Practical limit about 20 CFM

Pressure:  Intended to reach 1 foot water column (0.34 PSI / 2.9 kPa).  Able to go much higher.

Ergonomics:  A somewhat high seat is recommended.  In the video below the seat is too low and it's uncomfortable to play.

I/O:  1½" I.D. flexible vynil hose, with or without woven reinforcement.