This is just a couple of simple models to sort cards in. Both have 6 28mm slots to sort into, sized to a Dragon Shield sleeved card. 

The full model completely covers cards with some extra overhang, and the slim model allows about a half inch (13+-1 mm) of overhang. They're stackable, even between the full coverage and slimmer models.

Comes with a little peg/kickstand to give it about a 3.5 degree backwards tilt to help retain cards, and it should be able to align boxes for stacking as well. You should print at least two of these. 

The peg and holes do require a little bit of dimensional accuracy or post-print cleanup. There's a 0.2 mm tolerance built in and on my printer it comes out reasonably snug. 

The top interlocking pegholes usually need some cleanup from the filament drooping.