This is a 2U modular server rack unit.
The idea is that you add “Rails” to the unit based on the items you wish to use it for, and not being forced to have the same unit setup in the entire rack unit, you can mismatch rack slots based on your needs.
Rails:
Tray:
Extra hardware:
Mounting:
Printing:
ToDo:
The author hasn't provided the model origin yet.