A small file (a quality crystal file works wonders with plastic)
Print settings
All parts except for the spring
MUST be printed in PLA or nylon. PLA is the most slippery common filament. PLAs made with NatureWorks Ingeo 3D850 resin are the most slippery and will work best for this object, after nylon. PETG is too soft and sticky.
Layer height : 0.2
First layer height : 0.4
External perimeter first
Top and bottom fill pattern : Concentric
Table
Seam position : Aligned
When importing into PrusaSlicer, choose to import as a single object containing multiple parts (Click yes)
Set "Ironing modifier part" as a modifier and set it to enable ironing.
Bottom ring
Seam position : Aligned
Brace
Seam position : Aligned
Print on smooth PEI so it will glide better
Rollers (x4)
Seam position : Random
Make sure that your printer is properly calibrated, so that the seams won't bulge out. Otherwise, the rollers will simply not roll. There can be no bump or zit.
Skates and push tabs (x3)
Seam position : Aligned
Spring
Seam position : Aligned
Print out of TPU with settings appropriate for TPU
Post-processing
File away any overextruded bit of plastic on the top of the brace.
Assembly
The bed-side face of the brace will be the most slippery. That face should face the bottom ring.
Do not lubricate. Lubrication will reduce the performance of the spool holder.