This is 100 mm depth version of printed 10 inch server rack designed for printer with plate 250 mm x 200 mm (Prusa MK3), but some parts (rails) need the bigger one (Prusa XL).
Rack has standard sizes, see https://en.wikipedia.org/wiki/19-inch_rack
Rails can be stacked on top of each other. You don't need lines or heads, but each rail starts and ends with half U, and you can download them from origin model.
Shelves can be oriented up or down, but filled shelves are perforated (reinforced) from one side, so be careful about that.
There are two groups of shelves:
I use standard M6x16 screw with M6 nuts.
The author remixed this model.