K8400 Low Friction Spool Holder

Excellent design by sneakypoo. Thank you.

My remix fits the Vertex K8400 without modifications and without extra hardware, except for one M3x12 screw/bolt. As the original, it allows you to use several sizes of spools.

Since printers often print hole sizes too narrow, you probably need to resize the parts somewhat. Obviously, the ball bearings __must__ fit inside the core, and the core threads __must__ fit inside the nut threads. I resized the core part +3% in X and Y direction, and the nu