I needed a simple cord cincher, but couldn't find adjustable ones on Thingiverse. So I made a few designs...
This is the squared off version. I have a "rounded" version here which uses less filament:
(The cost of printing one is still considerably cheaper than buying a package off ebay.)
This "squared" cincher is made to use a leftover Ender3 bed spring, but you can customize it to fit whatever spring you have on-hand. Use the included f3d file (which is fully parameterized).
Ender3 bed spring dimensions:
Outer diameter - 9mm
Inner diameter - 6mm
Compressed length - 10.5mm
Uncompressed length - 19.4mm
The spring is retained with a friction fit, which holds things together until you get the cord through. You may need to adjust the fit to your specific spring, cord size, and printer tolerances. Enjoy!