I'm in the process of designing some new cases for the MiSTer (DE10-Nano) board with various configurations of addon boards.
This first one is a standard case for the DE10-Nano equipped only with the SDRam XS card. It's a case that uses passive cooling. There are generous vents on the bottom that lead to a couple wide channels integrated into the side walls of the case that allow any heat generated from the underside of the board to flow upwards and out the top. Side vents into those channels have been placed into the case walls, and the lid contains generous venting. The rectangle in the center will be home to a case label.
I've also designed the case to allow for very easy access to the SDcard. I don't know about you, but I am forever pulling the SDCard out to try a new core. Having easy access to the SDcard was very important to me. It's super easy to get the card out, and to put it back in (even with my big mitts!).
I'm in the process of "torture testing" this case. Heat is expelling nicely out the top of the case, and the case itself has only gotten slightly warm. Seems to be working as expected. Once I'm satisfied that it's functioning acceptably, it'll be available at COREi64 Shop for those interested.