Seatbelt Stop

My neighbor has a bum shoulder so he asked me to recreate a "thing" he made out of some webbing hardware. I made this instead.

He uses it to keep his seatbelt pulled out since he can't reach behind to grab his seatbelt.

The first version was printed in PLA and didn't hold up too well it's first summer. I'd suggest ABS at least. Nylon or any other higher temp material would also work well. 100% fill is also a good idea (even though it probably won't need any fill) since it's quite flexible.