Hairpin cotter pin rubber safety wire / Lanyard.

thingiverse

I run a business that offers machine and trailer rentals. I encountered an issue securing a metal chain to my cotter pins using hairpins, which kept disappearing when customers returned the machines. Steel chains and rings would frequently slide off and corrode, sometimes damaging the paint job on the machines' dashboards. To solve this problem, I designed "rubber chains" or rubber lanyards that fit Ø3mm and ø4mm hairpin cutters. These can be easily scaled up or down in size. I also created a smaller chain for use with keyrings. The designs are large enough to print on an Ultimaker 3 without support or brim. I printed my prototypes using Ninja-flex filament, which is strong and flexible, but prone to zipping when printing thin lines like the C-shaped loop around the pin. To avoid this issue, I set the wall line count high. However, I struggled with printing Ninja-flex until I purchased a PTFE Bowden tube, which greatly improved the results.