Gridfinity stand for a Brother P-Touch 550 labelmaker (my exact model that I designed this for is a P-Touch E550W but I guess this should fit other, physically similar models). The device pretty much exactly fits in a 3x6 gridfinity pattern.
I printed mine with standard settings (0.2mm layer height, 15% infill, no supports required) which worked fine. I inserted a filament change for the second color but that's obviously optional.
In case you are wondering about the label tape cassette boxes in the photo: those were not designed by me, it's this model: https://www.printables.com/model/302028-brother-p-touch-tze-label-tape-gridfinity-storage-
The author marked this model as their own original creation.