Rubik's Tangle 5x5, Version 1, 2, 3, and 4
Rubik's Tangle 1, 2, 3, and 4, Matchbox 1990.
(Box and twenty seven 2 inch cardboard squares.)
Arrange 25 squares in a 5x5 array so that edges match.
Each square has the same pattern of 4 tangled ropes that has two connections on each edge.
There is one square for each of the 24 possible combinations of the 4 colors (red, green, blue, and yellow),
and one duplicate square.
The only difference between Rubik's Tangle 5x5
Versions 1, 2, 3, and 4
is which piece is duplicated.
By taking three pieces from a spare set,
a single set of 28 squares can be made where three of the duplicates are left out to make one of the 4 puzzles.
Below is a set made by starting with a Version 3 and adding three squares taken from a Version 2;
the four duplicate squares have been labeled with a number on the back.
from: www.uspto.gov - patent no. 487,798
from: www.uspto.gov - patent no. 606,338