Pneumatics were used to make these pop-up toys by Year 3. You can see how they work from the back here:
The basic design used a cereal box. One side was covered in blue funky foam (neoprene) and simple shapes were cut out to make the scene. Children then made a pirate, jolly roger, shark or other monster and stuck it onto a lolly pop stick. The pnuematic system was then attached using masking tape.
This formed part of the Treasure Island themed work for the Telling into Writing project. More details about Telling into Writing on usefulwiki