Product Recommondation: DIN rail mount
The Up Board comes mounted on an aluminum head spreader plate, initially I looked at removing this plate so that I could use some of the available Raspberry Pi mounting options available, for me specifically, DIN Rail mounting. Then I thought maybe I'd just use the plate as the mount itself and went on a quest for generic DIN Rail mounts and came across one from Phoenix Contact, not cheap, but I have to say this is one quality piece of kit. It comes in several sizes and the 89mm version (UTA-89 Part #2853970) is just slightly longer than the Up Board base plate and slightly narrower in width, by just a couple mm either way. It's a heavy metal die cast mount that locks into a DIN rail like a vice, there is nothing cheap feeling about this product, heavy duty stuff. The mount has a multitude of mounting holes on it, perfectly sized for 1/8 blind rivets. With 3 rivets holding the plate centered to the mount this provides a very positive locking mechanism to a rail. My rail is mounted vertically and I had issues of a lot of DIN devices "falling" down the rail if you touched them. There is no such issue here, once locked in you can't move these at all. I think you'd probably destroy the board trying to pluck it off the rail without releasing it, and the release is easy to get to when mounted. The only real drawback is the price, at about $35 US a piece it's more than just about any RPi case out there, but for a lab or industrial type environment it's fantastic. I have my boards mounted in DIN rail 2U rack adapter mounted into a 2U wall mount and power the boards from a TDK/Lambda DIN mount power supply. One 6A supply seems to power 3 Up Boards just fine with a bunch of stuff stacked on them (3.5 TFT HATS, PiFace Relay2 Boards, USB - > SSD carrier boards) and seem to have no issue what-so-ever even if all 3 boards are powered up simultaneously from power off state. You could probably squeeze 6 Up Boards into the 2U rack mount adapter if you didn't use any of the long side connectors, possibly even with power supplies though it'd be close. Mounting them this way you really don't even need cases at all as the rack mount just functions as a case for multiple boards.