Designed this quick "adapter?" so I can hang my pull up bar from single hook in the ceiling. Diameter of the pull up bar is about 30 mm, I didn't have my callipers on hand, so I made the diameter of the adapter 32 mm and it fits okay. I attached it to the pull up bar with healthy amount of epoxy glue and so far it survived decent amount of pull ups (I used acetone to weaken the glue when I switched from V1 to V2, it was quite painless). Diameter of the rope used is 10 mm (basic climbing rope from decathlon).

V1 (green in photos): Stops rope from slipping in either direction. I made the diameter for the rope a little tight in my original version, it should be fixed in the uploaded file, but I also redesigned the whole thing…

V2 (purple in photo): Stops rope from slipping only in one direction (somehow it feels wrong to highlight these two words), which all that is needed when you have hook in the middle. Also doesn't need supports. Also designing the sleekest curve possible so there's zero chance of any chaffing along sharp edges was so much PAIN, hope somebody will appreciate it.

Printing:

I recommend using PETG, 3 perimeters and 100% infill for maximum endurance.

V1 needs supports, V2 does not.