The only supports needed are for the contact feet/pads. Stand on end to print. Container can be printed at .2 and up. The door is a print in place screw so make sure your printer's tolerances are dialed in and print at .2 or .24.
The sheet metal I used was 58x180mm. I glued a Necron black stone (I think that's what it is, still real new to 40K) on the end of mine for my army so I would be able to pull out the sheet easier.
The author remixed this model.
Mine is actually a redesign of Dreamreaver23's design. I used the same dimensions but changed the up the door to be a screw design.
Definitely go check his version out. His container does have more detail. I just made mine so it was an easy print.