Monoprice Maker Select Spool Holder Nut

A design for a replacement nut for securing spool holders to Maker Selects. OpenSCAD code (preview fails, click render): https://pastebin.com/0N5yiqNA

STL for a bigger spool holder that can hold almost every 1kg spool, unlike the one that comes with the printer: https://www.thingiverse.com/thing:1857904