I still have an original calendar cube from the early 80's in my collection, I think I bought it at a car boot sale ( US: flea market ) in 1988, and I never came across another. They are described as scarce in the book "Rubik's Cubic Compendium" , which my local library had a copy of in the early 90's.
This version, with red and blue text on white stickers:
http://www.twistypuzzles.com/cgi-bin/puzzle.cgi?pkey=1208
I remember analysing it, to see what mods would be possible. It turns out there's not much scope for improvement, the design is using a clever trick to get everything to work. It relies on the letter N being reversible, so it can be used at the beginning and end of the month, NOV and JAN/JUN. I did however decide it would be possible to also put the year on it - though limited to just three years, by having one corner-piece with, say, 1982/1983/1984, and then substitute with a plain white sticker for subsequent years.
I had it on my desk at work for a time in the early 90's, but people kept messing about with it, and I felt it may go walkabout one day ( like some of my other desk ornaments did ), so I took it home.
The "Rubik's Cubic Compendium" book is available online if you search, in djvu format. It's an interesting read, with some peculiar algorithms/techniques included ... something called a "Cambridge throw and catch" to solve the first two layers, and tables of algs for such methods as 'PLL then OLL' ( not recommended ... )
. Thanks for the review, and I look forward to other videos!
