I'm trying to get a wider version of this enclosure too.
Here is an actually helpful photo:
Left side: 61mm tall (measuring at the tallest part)
Right side: 41mm tall (I'm measuring right at the corner, so this is the shortest possible height on that side)
The thickness of the PCB is ~1.8mm and it fits into the slots perfectly.
So my question is: is this a standard type of enclosure? if so, what is it called and where can it be purchased?