Spool for flat ethernet cables. The two halves fit in and lock together snugly for a fairly stiff spool. The snap-in drill winding core has a hole for a ¼ inch hex bit so you can wind cable very quickly. Then you can keep the cable in place with the printed clips.
My cable is 7.1mm wide and 1.7mm thick. Smaller should be fine, but if yours is signficantly larger, this might not work.
Both ends of the cable can remain out and usable so that you don't have to unspool the whole thing to use it. Designed so that there are no sharp 90 degree bends of the cable!
Three sizes provided, large size (210mm diameter) fits a 50 foot cable pretty nicely. Small size (160mm diameter) fits a 25 foot cable with room to spare. Extra large size (235mm diameter) may be able to fit 75-100 foot cables, depending on the cable thickness. If you need other sizes or have issues with the tolerances, let me know and I'm happy to modify the model.
Locking mechanism uses xavierasx's Bayonet Lock Connector library: https://www.thingiverse.com/thing:6536797/files
Instructions for use
Step 1, insert the cable into the half with the small opening for the cable:

Step 2, put the other half of the spol on top. Line up the little open/close direction indicator icons first, then rotate left until the top half starts to fall into lock grooves. Push down, then rotate clockwise until the halves click into place:

Step 3, click the drill winding core in place. Line up the gap with the cable:

Step 4, wind!

Step 5, remove core to reduce bends of the cable, clip the ends of the cable into the sides of the reel:

The author marked this model as their own original creation.