3D models in STL format need to be converted to gcode, a text file of instructions that guide the printer’s actions. Gcode conversion is accomplished by a “slicer” program. I used the free PrusaSlicer to generate Gcode, but the Cura slicer will work as well.
Filaments can be sliced, starting with generic profiles for PLA, PETG, and Flex respectively, and modifying the profiles with the settings below:
Face on bed: no change (flat side down)
Configuration: generic PLA
Layer thickness: 0.2 mm quality
Infill: 15%, cubic or gyroid (for insulation)
Face on bed: upside down (flat side down)
Configuration: generic PLA
Layer thickness: 0.2 mm quality
Infill: 15%, cubic or gyroid (for insulation)
Face on bed: upside down (flat side down)
Configuration: generic PLA
Layer thickness: 0.1 mm detail (to produce smooth serpentine paths for the polyethylene tubing)
Infill: 15%, cubic or gyroid (for insulation)
Seam position: Align to rear
Face on bed: largest side down
Configuration: generic PETG
Layer thickness: 0.2 mm quality
Face on bed: upside down (flat side down)
Configuration: generic FLEX, modified with settings below
Layer thickness: 0.4 mm quality
Infill: 100% rectilinear (or 95% to reduce build-up on nozzle)
Seam position: Align to rear
Small perimeters: 20 mm/s
External perimeters: 20 mm/s
Top solid infill: 30 mm/s
Acceleration control: 200 mm/s (all accel. settings)
Default extrusion width: 0.9 mm
External perimeters: 0.9 mm
Slice gap closing radius: 0.098 mm