I designed these mounting brackets to install divider walls in my IKEA rack.
Brackets have thin elastic walls so they can bend around the 18mm square profile and be tightened in place with one M4 screw and nut. On the opposite sides there are holes for screwing wall plates to divide the rack into separate compartments. There are no metal parts in contact with the profile so there is no risk of scratching it

one 180 degree bracket and two versions of 90 degree brackets are available.

one tip for printing is to avoid alligning Z seams on the joints where the bracket bends, this can cause the joints to crack.