A question block originally made by Matt Sauer (Forehead), which is a great design by itself and is truthful to the 8-bit inspiration, remixed with th...ree adjustments:
Made it 8 times larger (twice the length for each axis)
Separated the question-marks from the rest of the cube to make it printable with 2 materials/colors (I personally chose red for the box and white for the question-marks)
And with the coin-slot size is corrected for the largest Kuwaiti-currency coin (100 fils).
This is a present from me to my eldest son for losing is first tooth :)
Updated 25-09-2016:
Separated the box and lid into several files, for convenience.
Made the box wall a little thinner without compromising structural integrity, to save time and filament.
Corrected the size of the coin-hole.
Corrected fitment of lid.
Corrected the lid platform so that it doesn't string without supports.