I was having under extrusion problems with TPU on my a1, so I designed this replacement spool holder that lets the spool roll very easily.

This uses two standard 608ZZ / Skateboard bearings and everything else is 3D printed. Simply assemble per the exploded and section view and enjoy!

I recommend printing with at least 4 walls and 50% infill since the thin shaft for the bearings does not leave a lot of room for material.

As a disclaimer, I've only just made this. I don't know how well it will hold up, but it seems to handle the load well enough.