Not Earth-shaking, but maybe useful for many different applications such as actuating hatches, deploying legs, recovery deployment, stabilization. I'm creating a low pressure (10 psi) miniature pneumatic system to retract and extend legs on a model-sized rocket. The 1/4" pneumatic actuator produces about 0.25 Kg force at 10 psi. Using inexpensive air solenoids that operate at 5 VDC. Here's a 5 minute video that shows my first try at developing a low mass system.