My first design from scratch!

Easy print, just print both parts as is with no support, put your cable in the centre piece gap and insert the piece into the centre and press until it clips in. Then centre your cable and twist the centre knob.

If it is tight give it a few twists and it should loosen up a bit.

If you cant get the bottom to clip in then just file the edges of the bottom at a 455 degree angle and try again. You can apply quite a lot of pressure without it breaking.

To unwind/extend the cable pull the cable at either end.

Edit: V4 Screw now can be clipped in easier

Tip: if you find it hard to turn once clipped in just take apart and rub the contact points with sandpaper to round them slightly.