The Buchla MARF - Multiple Arbitary Function Generator is one of the rarest of Buchla modules.
I would love to find a real one (or even see one for that matter).
This modern version is the closest I have come to one.
Its a great module. This is Roman's rev 1 of the 248r.
these are some pics of the roman build MARF
Some videos of how it should work
internal stage addressing