I'm afraid this case doesn't fit. I have the standard Arduino Mega 2560 (genuine from Arduino), and had to cut ~1.5mm of plastic from the behind the USB in order to get it to fit. Only after great effort and prying (broke off two of the 4 tabs) it came on, ready to pop off at the slightest touch.
The screw hole placements are also off from the holes on the board by about 0.75-1.2mm. This allows one single screw to come on if you pick it right, and perhaps not even given the "snugness" of the case.
I printed in PLA at 3000mm/min, 0.2mm, and bar from the clearly wrong measurements, no aesthetic issues came up at all. Sad, really- it's a very elegant looking little case.