I find the spool holder that came with my MINI+ to be frustrating--constantly having to adjust the width so that the spool's edges ride on the bearings. So I made this. It needs no adjustment for width.

It uses the bearings that came out of the original spool holder. The holder, or caddy, as I like to call it, will accommodate spools up to 80mm wide. The widest spool I have is 76mm.

Printed at .2mm layer height, but .25 should work fine.

You'll want to attach some stick-on rubber feet on the bottom.

I made mine out of clear PLA because I have a 1kg spool of it that I'd otherwise never use up.