This design uses added internal perimeters to increase the print strength.  I cannot recommend using this to hold body weight, but with the right materials and print settings, I (220lbs) was able statically hang off of one.  If you aren't planning on weighting it, print settings don't really matter.

The bracket is sized for:

1x ½" bolt hangar

1x ½"x1.25" hex head bolt

1x ½" washer

1x ½" nylock nut

4x ¼" lag bolts (length depend on how you mount it)

4x ¼" washers

Any climbing hardware is up to you, go crazy!

Print settings:

PETG

.4 mm nozzle

.3 mm layer height for strength

4 perimeters minimum

5 top/bottom layers minimum

15% infill, cubic or gyroid

.stp file available at request, please attribute if you remix.