It took me two afternoons. The quality of the build is impressive, but what impressed me the most was the Raspberry Pi itself. It loads much faster than I expected and it is very easy to upload the roms wirelessly from my Mac via SMB.
Below is a small gallery of the building process. It starts with the frame and ends with the wiring.
I’d advise it to anyone who enjoys building things and playing retro games. Retropie doesn’t only emulates Mame roms, you can find the complete list of supported systems here. You don’t need any knowledge in electronics and no soldering is required. With a bit of logic, you can do anything.