When our extension club did a crayon quilt, we used simple patterns from a coloring book, ( rabbits, horses, teddy bears, fish etc.) Then you need to use genuine Crayola crayons, not the cheaper ones. After coloring to your satisfaction you place between two pieces of paper toweling and press on Cotton. The excess comes off on the paper and if it doesn't look as dark as you would like, you recolor and then go through the paper towel method once again.
We did this when I was in the Girl Scouts years ago on pot holders for a Mother's Day project and I remember they lasted for years washing in the the wash machine. Getting back to the quilt, we put sashing around each block and made a child's quilt which we sold chances on. crazydazy