These are mounts for the Master Sword found on Thingiverse here: https://www.thingiverse.com/thing:1449187
I designed these to hold the sword on my back because at the time I didn't have enough filament for the whole sheath, but I imagine they may be useful for another purpose as well.
Recommended print quality at 0.15mm and 10% infill. No supports or brim needed.
The author hasn't provided the model origin yet.