NOTICE: for a new and improved version, please see my updated design (https://www.thingiverse.com/thing:3372003)
I'm in the process of making a Prusa Bear MK2S with RAMPS, so I needed an enclosure to fit my needs.
I've made it 24mm longer, to hide all the electronics and it's also possible to add a 40x40 fan inside to cool down the drivers.
Also an aperture to get out the LCD cables.
Anyway, just slide the Arduino inside the enclosure and fix it with just one screw.
Happy printing :)