a.k.a. Rubik's Hat
Matchbox circa 1994.
(plastic, 2.4 inch top, 3.75 inch rim, 3 inches high)
Six discs, each with nine slices,
can be rotated.
In the initial position,
with the letters
* R u b i k
in a vertical line down the outside,
no rabbits are visible when turning over the hat and looking in the bottom with light behind.
The goal is to rotate the discs so that nine rabbits, one in each slice, can be seen.
gives an analysis that shows the following solution to be unique
(this view looks inside with the rim of the hat facing up):