After I free-motion stitched around the butterfiles in the center rectangle and the two border pieces, I turned the pieces over and saw that the yellow with the varigated thread were too stark. So I grated crayons onto each the yellow side of each piece. Then heat-set them by pressing with a hot iron several times. I kept the grated crayons off my pressboard pad by using parchment paper both beneath and atop the quilted pieces.
The tabletopper should be able to be laundered a number of times before there is any sign of fading.