Here's a picture hanger I designed to replace the metal 3M hanger from 3M (last photo).

I needed to hang a picture with a single d-ring hook, much like the one shown above. All other 3M hooks I had on hand were too large, so I designed a heavy-duty hanger that will not break even when printed using PLA.

I can't say as to how much weight it will hold, but I suspect it's just as strong as a regular 3M hook.

Print Settings

Rafts:

No

Supports: 

No

Resolution:

0.12

Infill: 

50% Gyroid

Filament: any PLA

No supports needed, just print using your favorite "Fine" settings for extra strength.