Date: Fri, 10 May 91 22:58:29 EDT
From: Andy Latto <latto@lucid.com>

On the other hand, I would be willing to pay a fair amount of money for
an order 21 cube. :-)

You can't make an order 21 cube, or any cube of order 7 or higher.
When you turn the top layer of such a cube by 45 degrees, the corner
cubie will not touch the other layers at all, so there's
no way to keep it attached, and it will fall off.

Assuming the current technology, anyway. But imagine a less passive
approach. Suppose each cubie had a cheap microprocessor, and some
little latches. Normally cubies hang onto their neighbors, but when
they notice you are applying torque, they let go of their neighbors
in just that one direction and hang on for dear life in the other two
directions. The latches can also be conducting in order to convey
the necessary actuating power from a centrally placed battery.

--Wild and Crazy Guy