I stamped the whales on polka dot paper, cut them out, and then popped them up with foam dots - quite a few steps for 30 cards, but it was worth it!
I made the box my measuring the size of the stacks of cards side by side and then scoring to the correct height. I also placed an extra piece in the bottom to stabilize it a little more and made sure to use 120lb cardstock. I decorated the top and added a fun tag using a clothespin.
Paper: Solar White Cardstock 120lb (Neenah); Bitty Box and Bitty Dot Patterned Paper (PTI)
Ink: Black Ink (SU!)
Stamps: Whale and Big Thanks (A Muse Art Stamps)
Extras: Embroidery Floss and Clothespin (from my stash); Bling (Bazzil); Border Punch (Martha Stewart); Large Scallop Punch (EK Success); White Ribbon (My Favorite Things)