Instead of crayons to make a symmetrical design, try using paint. Have
students fold a 12" x 18" piece of manila paper in half, then open it up
flat. Using three "squirt" or paint bottles, one each of red, yellow,
and blue tempera paint, go around the room placing three globs of paint
in a triangular formation near the center fold (the line of symmetry) of
each paper (I do not recommend letting the students do this part!).
Have students carefully close and gently rub the paint inside the folded
paper, then open it up to dry (also look for formation of secondary
colors). When the paint is dry, have students use the color blots as the
basis for a design, drawing details with crayon. I just did this with a
5th grade class yesterday and we ended up with clowns, transformers,
angels, fish, burning houses, and trained seals.