To easily integrate the BH-101 amongst other instruments, I had to choose between the standards available.
I went for Eurorack aka the Doepfer A-100 system. A bus with +12V, -12V and +5V is really the core of it, along with physical dimensions to fit in the racks.
Eurorack requires a faceplate of 128,5mm x a multiple of 40mm, drilled with the holes for jacks and pots.
I found the price for a pre-cut piece of aluminium quite expensive (about 25E for 128,5x80mmx2mm) so I decided to buy a whole sheet and cut it off myself. I found this 250mmx1000mmx1.5mm for less than 10E at the local hardware store.
So I cut into the aluminium with my Dremel and manage to get a decent cut. Far from perfect but good enough.