This is housing for Zubax Orel 20, advanced ESC (BLDC motor controller) with doubly redundant CAN bus interface, designed for unmanned aerial vehicle. More on that here:
Printing: no special printing requirements.
Assembly: put the pcb in, screw it with small screws, insert two pins of the lid in relevant holes of the housing and then slightly move the side wall of the housing and slide the central pin of the lid into the hole. That's it.
Source sketchup model included, so you are welcome to modify it if you need.