This is just a simple clip to keep a seatbelt clip in place.
Build with support as this does have an arc to it to place less stress on the plastic. I have printed this in PLA and it works really well. The slender plastic arms only bend slightly which is an improvement over other clips that I have seen.
** Revision 2
After using the first version I noticed some issues. The "arms" tended to bend out more than I thought they should so I increased the "gap" by 1mm and shorted the arms too make it easier to install and remove from the seatbelt.
** Revision 3
Increased the width of the "arms" to strengthen them slightly.