Well, to my knowledge, if you were to use gravity (or inertia, or even latex tubing... whatever, really) to your advantage, you could power a pneumatic actuator in one (of the two possible) direction (connect only one side of the actuator to the solenoid, whether it's double or single), which would allow you to power two pneumatic actuators using only one solenoid.
Uh. Please correct me if I'm wrong.
