I made this hook device to hold plastic grocery bags outside on my back porch to hold “trash” that I didn't want to bring inside my house until trash day. I added the screw hooks to ensure the plastic bag wouldn't blow away in the wind.

I printed this with PETG and used base support only. Support material is easy enough to remove and has held up decently well outside so far. One has about a ~4mm gap while another has a ~7mm gap to latch over whatever it is going to hang on. The gap and overhang portion should be easy enough to modify if you need more in a CAD tool. 

The 4mm one fits snuggly on my Quartet glass whiteboard if you are looking for ideas on what to use it for. Thinking of making up nameplates for the glass board for “Do Not Erase”, “Contact Engineering”, etc.