Cut two identical length pieces of different colored boondoggle strings and place the midpoint of one string over the midpoint of the other string in an “x” position.
Take one end of the string that is on the bottom of the “x” and fold it over the string that is to its left. Repeat until there is only one side of the string left and thread that end through the loop farthest away from it.
To continue the keychain, make two loops using the same color and thread the other color through the loops going over the loop nearest to it and under the loop that is farther from it. Repeat until desired length.
Tie off boondoggle by tying a regular knot and then following that with an overhand knot.