Here’s my solution (it’s the one from the book):
And here’s the link:
Description: By putting ramps on either side of a bit (pointing inward), you can flip the bit and the ball ends up in the same place regardless of the starting position of the bit. In this puzzle, all of the bits have ramps on either side. An added bit on top directs the first blue ball to the first column of bits, then the second column of bits, and then a red ball flips the third column of bits.