Bags and stuff kept falling off this closet rod I got from Lowes, so I designed this end cap/hook to stop that. The inside diameter of the rod I have is 31mm, you could resize it to fit a different rod. I printed it with 20% infill and 4 walls in petg. I'm sure pla might work as well. I'll link the rod I have below, I'm new to 3d printing and modeling so I'm open to suggestions and tips.

https://www.lowes.com/pd/Blue-Hawk-72-in-L-x-1-3125-in-H-x-W-Black-Metal-Closet-Rod/1001378470