Cmetrick Too (Hard)

Patented by D. Rom 2004, made by elogIQ.
(plastic, 3.5 inches with 1.5 inch diameter balls)

Each of the six balls can rotate in each of the three directions. Each pair of adjacent balls shares a disc (so there are a total of 20 discs), and rotating a ball causes the shared disc or discs to move and be replaced. When solved, each ball shows a single color (red, blue, green, or yellow) and the hidden discs are all white.

A harder version of the puzzle, called Cmetrick Too Hard (two views shown below), has dots in the middle of the discs that must be the same color on each side of the puzzle when solved.

The puzzles come with solution hints, and Jaap's Page presents a solution.

Further Reading
Jaap's Page, from:
Jaap's Contest Page, from:
Rom Patent, from: - patent no. 6,773,011