This fits the base of a “3M Command Large Utility Hook”. I kept breaking the originals with towels so I printed a replacement, which should be a bit stronger. I printed in both PLA and PETG, but the PETG may be a little too flexible. The PLA version seems sturdy

Should be printed on its side. Model has some built in supports to help the big hole in the middle of the print. Just clip them off after printing. The slight overhang at the tip of the hook shouldn't need support, but you can add some there if the underside is misshapen.