Socket on top is 1.5 inches square + tolerance. Design can be stretched in all axis' in the slicer for a custom size and height.
No less than 20% infill to maintain high strength. I recommend increased perimeters (3+) and top layer thickness (5+) for longevity.
I have been using them for about 3 months on a bar and they are extremely stable with no sign of weakening.
The author hasn't provided the model origin yet.