I was looking for an easy project box to host projects based on Arduino (in a minimal realization like this one).
I came across some old VHS tapes and the plastic case seems really easy to manage (make holes etc.).
It's also very easy to remove the transparent sheet: simply rip it off:
The resulting case is really nice:
There is also plenty of space inside:
Moreover it closes quite firmly but is easy to open whenever it's needed.