Prints in one piece, no need to snap anything together, just print and clear any supports from the outside.

Warning -- Pictured print was original model before updates
(see below for what updates have been made, preview images show updated model)

I liked some of the latching boxes here on thingiverse and tried to make it into a MTG box.
I started with this box:
http://www.thingiverse.com/thing:82620

Unfortunately for me, somehow the hinge was all wonky in my file so I had to remake the hinge from scratch (good learning experience) and scale the latch. I ended up with a piece that barely fit on my printer...in fact it didn't fit. Half-way up the print it suddenly shifts about 1mm to the side.

Edit Jan 17,2016
I finished the first test print on LOW quality and it came out very well! The hinge and latch both work beautifully (again thanks for the latch user anewsome) however I did notice some issues. Aside from my printer shifting the model to be able to print it the top and bottom didn't exactly line up because I'd never done a hinge before. I fixed this alignment problem.

In addition though I enjoyed the idea of using the area with the various mana symbols as a exile, I did NOT enjoy that when the box was closed and latched, the dice were able to roll around if you flipped the box upside down. So I lost the exile area and made it so the dice wont roll even if the deck box is flipped.

I also added another finger hole down far end of the library/graveyard. You could say it was for 'ease of use' but really it's just more for a symmetrical way to use less filament (and print faster).

I had a great deal of difficulty removing the supports from the latch, so I rounded the bottom of it and moved the tap symbol to the side of the box and adjusted the Magic M to fit the new top lid.

Edit 2
Adjusted to make it slightly easier to remove the D20 dice.