My wife has a thin flexible tape measure she keeps with her knitting stuff. After watching her winding it up to put with her things, I suggested a small winder for it. A few minutes with OpenSCAD and I had a design. Luckily, the first print worked out great! The parts don't snap together, which would be a nice touch. Also, for extra awesome points, it should really have some planetary gears so that a single rotation of the winder would be like 27 rotations of the inside core.