Wrap a piece of construction paper around a paper towel tube and tape it in place. Use two pieces of construction paper, if necessary.
Cut four, 2 1/2-inch slits into one end of the wrapped tube. Align the slits so that each pair is opposite the other.
Draw two triangles onto a piece of card stock. Make the triangles approximately 4 inches wide by 5-inches tall.
Cut a slit into the top angle of one triangle. Make the slit one-half of the triangle's height. This will be triangle "A." Cut a slit into the base of the other triangle. Make this slit about one-half of the height as well. This will be triangle "B".
Insert the top angle of triangle "B" through two of the slits in the wrapped tube.
Insert the top angle of triangle "A" through the other two slits in the wrapped tube. As you do so, triangle "A" also will fit into the split base of triangle "B," forming the rocket's base.
Draw a circle that is approximately 4 inches wide on a piece of construction paper and cut it out. Cut a slit anywhere on the circle, extending from the edge to the center of the circle.
Bend the edges of the circle's slit toward each other to form a cone. Tape the two sides of the slit to secure it.
Place the cone on the top of the rocket and tape it in place.
Decorate the rocket with stickers and markers, if desired.