My dog managed to get a hold of a mitten and destroyed a d-ring. 

I therefore needed a ned d-ring to replace the old one, that was sewn on. This d-ring slots on to existing loops, no needle and thread needed! 

Height, width and thickness can be adjusted. 

I printed it with a extra hard TPU and 100% infill, i guess any other filament that can handle being outside will work just as well.

V2: Added a fillet around the edges.