These are modular card trays designed to hold Dominion cards. You can snap them together to keep the trays from sliding apart. For storage, they stack on top of each other (with or without cards inside) and are easily held together with a rubberband. This design was derived from the trays I made for the Settlers of Catan cards (http://www.thingiverse.com/thing:1181967).
This should fit any other cards that are 91mm x 59mm or smaller. I will hopefully have time to expand the design to work with cards of other sizes as well.
I also added a lid part incase you want something to protect the top of the cards while in storage.
Here is the quantity of trays you'll need to print by depth:
11x 5mm - For the standard (Action) cards & the Dutchy cards
2x 8mm - For the Province cards (6 player amount) & Trashed cards
2x 12mm - for the Gold, Estate & Curse cards
1x 16mm - For the Silver Cards
1x 22mm - For the Copper Cards
Be sure to check my other designs for more board game parts!
The parts are designed to have a little clearance in the dovetails so they'll go together nicely. If yours come out too tight, you may need to lower your flowrate multiplier or lightly sand the interfering faces.