It's basically CongoJoe's stacking case modified for the Raspberry Pi 2. I needed one for my new Pi 2, and I like his simple yet functional stacking mod for the original Adafruit Pi Box. I've added some breakaway slots on top for easier access to the GPIO, screen and camera contacts. There's not much material around the GPIO slot, so be careful if you decide to use it. Or redesign the whole thing. Putting the slots in the sides of the case would eliminate the problem and make stacking cases with cameras or screens or other I/Os possible. Use 3mm thick material, like the acrylic in the pics, for a snug fit.

This was laser cut from a 3 mm acrylic sheet. The slots and snap locks have been carefully adjusted through trial and error to fit this material. (Tip of the hat to my friend Fredric for patiently and repeatedly adjusting stuff on the go by the laser cutter.) The Pi itself can be fastened with screws to the base of the case. This isn't really necessary, as the fit proved to be quite snug as it is. Take care to mount the short end with the slot for the micro SD card the right way. The card sits slightly off centre on the Pi 2. The breakaway slots for the GPIO and other contacts haven't been tested, and I think the GPIO slot looks particularly flimsy, so be careful if you decide to use it.