This design is a spool holder for the composite filaments from "The Virtual Foundry".
Those filaments are brittle and need to be positioned in a specific position on top of your printer. This spool holder is designed to be attached to a 20*20 aluminum profile and provide minimum resistance by using ball bearings to hold the spool tightly.
To make this you will need 9 Ball Bearings 624 (4X13X5mm) and 15 M3 screws (10 to 20mm). I can provide a model using M4 screws if asked.
You will also need 4 M5X10 screws and T nuts to attach to the aluminum profile.
The virtual foundry spools have a center diameter of 66mm and this design will not work well with smaller spools (most of them).