2018-10-27 Update I got some advice on a french forum. You case use kite string as wire for cool rendering and strength.
2018-10-04 Update I added small discs to encase the wire/cable that won't go into the winch case.
Here's a mini RC winch for a N20 motor.
You'll need two parts from other designers:
The hook: https://www.thingiverse.com/thing:14653
And the gears generated and adapted from janssen86 OpenSCAD library:
It will fit 1/8 until 1/12 models and can be scewed two ways (bottom or back).
The metal parts are:
4 x 50mm m3 screws for the main body
2 x 8mm m3 screws for the front guide
The rope axle is made from a 4mm brass tube which is forced into the 16mm gear.
I made a hole through it by pinching a little with a cutting plier and a 1.5mm drill.
use 1.2mm width for the top/bottom/walls