Edit: Sep-19-2016: changed the design to metric.

This is a super duper hanger for the Flashforge Creator Pro and similar printers. This design has a few advantage

• Bearings based, virtually zero friction.
• Easy to mount and remove the spool. No screwing required.
• Easy to install and remove holder from the printer (e.g. in tight places)
• Fits all common spool form factor and spool holes, including Hatchbox spool with 1" hole.

Printing: print in the orientation of the provided STL file. This orientation will provide the max strength. I printed with ABS, 4 bottom/side/top layers, 0.2mm layers with 0.4mm nozzle, 20% infill and support material from the printing bed to that large round bump.

Materials: M6*90 screw (e.g. https://www.amazon.com/gp/product/B0143ACXD4), 4 X 626 bearings (I prefer the plastic/glass type, search ebay for '626 Plastic Nylon POM Ball Bearings', they turn smoothly, open don't require lubrication, don't rust, and light weight), and an M6 hex nut.

Assembly: debar the spacers and other holes (use a debarring tool such as Shaviv or a large drill bit) insert the bolt into the base, inserts the spacers and bearings insert the end piece and the nut and tighten everything.

Verifying your assembly:

• Make sure that all the bearings turn freely. The spacers are designed with chamfer at their ends to make sure the touch only the center part of the bearings.
• Make sure the end piece is well tighten and that it is pointing up. If it doesn't point up, release it, release, turn the bolt in the base a third of a turn or so and tighten again.