For each caterpillar section, place flat sides of cakes together.
For the eyes, press a gummy circle candy to a gumdrop circle using canned icing to hold the pieces together. Cut two 1-inch-long pieces of fruit roll. Cut slits into fruit-roll pieces to make eyelashes. Use icing to attach the lashes to the back of each eye. Use icing to hold the eyes to the top cake on the head section.
Cut a 2-inch piece of licorice lace for the mouth.
Cut a piece of twist into two long, thin pieces for antennae. Press a miniature marshmallow over the ends. Push the antennae into the top of the head.
Cut twists into thirds for legs. Push gummy circles onto legs, and push legs into body.