Designed these a couple of years ago for organising around the house. Good for any electrical leads, on equipment or just extension leads, storing rope, snatch straps, or anything you want to simply tie off in a similar manner to a reusable zip-tie. Best filament I've found is Esun 87a E-flex. Can be done with 95a TPU but its not as elastic so results aren't as good. 
 

Print these 100% infill rectilinear

No supports