I updated the last design myself. I cut off the back and played around with a few options for a hole to attach to a key ring. The triangle on the back is at 45 degrees so no supports are needed.

After a few breaks of my own and a few commenters suggested stronger attachments, i made the loop solid and recommend to print in petg abs or asa. Check out the new version here https://makerworld.com/en/models/1975180-stronger-ball-holder