Spool brake

I found when printing with TPU (and I would imagine any flexy filament) that even the slightest pull from the extruder would make the spool spin too much, tangling the filament around the holder. This basically locks the spinning part in place. Made to go with https://www.thingiverse.com/thing:4826849 which is itself a remix, so will likely work with multiple spool holders.

Use TPU for the smaller bit and PLA for the bigger
Will need an m3 bolt maybe 15-20mm and I used a spring from a mechanical keyswitch
The bolt should slide easily through the top. Pic is of earlier version that was a bit too big

Printed the smaller bit set like a bridge on the build plate with supports
Larger section printed flat no support

I used a brim for everything but was having adhesion issues so YMMV