Lou, another technique that I found that works well for the puzzle is to finish the whole pen with CA, then very lightly laser the alternating pieces in a tight hatch pattern. This is just enough to take off the CA, and allows the alternating pieces to absorb some dye or dyed CA without affecting the whiter untouched pieces. I found that 2 drops of black and one drop of brown dye make a nice dark color that contrasts very nicely with the raw pen color. I'll see if I might get some time this weekend to do one. I've tried a lot of experiments with scrap pieces, and I think this combination will really bring out the puzzle piece contrast. This assumes that there are four pieces going around the pen so that alternating pieces can contrast.