You can make your own roller-box TV out of a small empty gelatin carton. Cut a 2″ x 2 1/2″ window in one side of box (see illustration). Lay box (window side up) on a 10″ square of aluminum foil, fold foil around box to fit snugly, and tuck it inside window. Make two snug-fitting holes in each side of box as shown. Insert two short pencils or 4″ long dowels through holes.