This is a Ceiling grid clip, for a standard 1" ceiling grid, typical of commercial offices or stores. It has a 4mm hole for mounting hooks or zipties or whatever. Great for mounting birthday, holiday or scary Halloween decorations.
I used 0.2mm resolution, and 40 percent infill with supports, just to bed, hole did not need supports if on top. I printed it hole side up, bracket side down. Vary the infil amount to make it flex more or less.
Autodesk Inventor was used.