improved spool roller pair // monoprice select mini mspm // 608 skateboard bearing

improved clip-on place spool rollers
angled stopper contours to the shape of stock MPSM spool holder, keeping it from sliding

[2020 update]
applied "compliant mechanism" to the design to help with the brittleness of PLA

holds two (2x) 608 roller bearings on each side
(those dollar store fidget spinners are a good source of these)