The adapter is designed for 140 mm spools on an adjustable spool holder (https://www.printables.com/model/395673-spool-holder-for-prusa-mini-flexible-no-logo).

Non-printed parts:

• 2 x ball bearing 608 (8 x 22 x 7) - per spool
• 2 x screws M3 x 25
• 2 x nut M3

Printable parts:
1 x bearing holder Left
1 x bearing holder Right
1 x center part

PLA, PETG filament is suitable for production. Layer height 0.3 mmm, infill 15%.

https://youtu.be/7_El1bIgvYk