So I've just had an issue where I designed a nut into a FDM 3D printed part that's just an annular boss on an otherwise flat plane. I didn't want to add thread geometry into the print or with a tap after the fact just to save some time and effort and it's also unlikely that the resulting threads would be any good.
The issue with this design is that depending on the details of the annulus geometry, you could break the print when tensioning the bolt.