Customizable Fan Shrouds - Inlets and Outlets

My purpose for this is for a multi-fan simracing windsim setup. I found various inlets and outlets, but nothing customizable for combined a square, circular frames in all the sizes I want to use (80, 92, 120, and 140mm).

This fan inlet is a bellmouth which reduces turbulence of the air. The parameters work well, but I'm sure there's room for optimization.
The fan outlet uses a default angle of 15 degrees from vertical with a honeycomb pattern.

Vertical outlet shrouds are possible by setting outlet_diameter = inlet_diameter.

The stl's use 1.2mm walls which should work well on both 0.6mm and 0.4mm nozzles.

Tested

• 80mm:
  Jamicon JF0825B1UR (no PWM, doesn't work well with PWM motor drivers)
• 92mm:
  Noctua NF-B9
• 120mm:
  Noctua NF-P12
• 140mm:
  Noctua NF-A14, NF-P14s, NF-A14 iPPC
  Reduced size version to fit 220x200mm printer bed size

Untested

• 40mm
• 50mm

Versions

• 1.1
  Increased curve resolution
  Inlet size based on golden ratio (slightly longer, easier to print overhangs)
  Cleaned up code

Additional source for the bellmouth: https://github.com/kenbarbour/SCADVelocityStack/blob/master/velocity_stack.scad

This was initially inspired by the 140mm Max Airflow Fan Housing for Sim Racing by svideo, but it wasn't customizable for smaller sizes and bigger nozzles.