This helps to fit Oxberg door onto old Billy bookcase (pre-2015 model). Normally it leaves ~1cm gap between doors. This pad offsets it a bit to make the gap smaller. Adjust further with hinge itself to make nice fit.
It's really just a pad, anything will do. This was printed on MINI, black PLA, 15% infill, 2 perimeters.
The author hasn't provided the model origin yet.