I bought my first 2 kg Prusament spool recently and wanted longer rails for my spool holder so that it would take the bigger spool. These are sized so that when they're flush with the rollers, the 2 kg spool fits. The length can be changed with a user property in the Fusion 360 file. I printed them in PETG on my Mini+ and the fit is snug but not so snug that they require force to fit or remove.
The author marked this model as their own original creation.