I made this case to hold an arduino uno for a project I wanted to wall mount.

There are posts inside the case to hold the board in place with space behind it for all the sensors and wires I needed, and a 9V if you don't have too much else. The lid has posts that come down and meet with the ones on the base to hold the board securely.

I also included a snap fit base that can be wall mounted with screws or command strips so I could have easily remove the arduino for updates without having to take it out of the main case.