The original profile from the design of the Prusa i3 printer.
In addition, M5 threads are already made in the corner holes.
Included:
Profiles 30x30 mm, height 100 mm
Profiles 30x30 mm, height 50 mm
Profiles 30x30 mm, height 20 cm
T-nut with M3 thread
T-nut with M4 thread
T nut with M5 thread
The author hasn't provided the model origin yet.