I made a modular spool system for my MMU3 and Prusa Enclosure with bearing rollers.

Print the stands as they are oriented in the .stl

The Spool Roller for 2kg has a indent to support 1kg whilst keeping it centred. 

Print with 0.2mm layer height and 3 perimeters with 15% cubic infill.

The bearings are 8mm bore with 22mm diameter and 7mm thick. Good friction fit and doesn't roll “off” when there's a spool on.

The Bowden mount fits a M10 connector.

See the pictures for my setup. The 2 kg one goes on the back (when placed on the right hand side facing the enclosure) and the 1kg stands with attachments on both sides connect to it and one another with the front one being one with attachment only on one side. Mirror the first and last one for different configurations.