I just saw this over on Matrixsynth. It's from an ebay auction for a Moog Memorymoog (WANT!) but what is interesting about this auction is that the seller is throwing in a photo that he took in the Moog factory in the mid 1970s, heres what he says:
"I worked for Gibson Guitars in the 1970’s and our plant manager knew the Moog plant manager thus while on vacation I received the gold plated guided tour when the Memory Moog was in development, and Mini Moogs/PolyMoogs were on the assembly line. I have included a picture of some concept drawings of the Memory Moog"
I have posted about these prototype drawings before here