To make, have your child do a line drawing in black marker on a piece of 8 1/2-by-11-inch white paper. (The more detailed the picture, the better.) Bring the drawing to a print shop, such as Staples Copy & Print, to enlarge the image on a wide-format printer. (A three-by-four-foot print like the one shown here should cost less than $10.) Tape it to the wall or lay it on the floor, then let the kids unpack the crayons and unleash their creativity.