Hi. I'm a high schooler from Oregon, and I'm in a bit of a dilemma right now. What I'm trying to do is make a 5x5-pin tactile display for a high school physics project. I currently have a Makezine controller that can sink 1A @ 12VDC per analog output, and control 2 stepper motors or 8 servos at a time, for sure. How I want the thing to work, though, is have its surface be bubble wrap for this first prototype, and I will empty or fill each bubble by opening or closing miniature valves attached to each, and then use just one master pump underneath to constantly oscillate, moving up and down to fill or empty cells that have open valves. Actually, now that I think about it, I'm probably going to have to use party balloons for the pins. And, here's a diagram: http://img441.imageshack.us/img441/2707/crappyschematicnf6.png [Broken] Even though I'm dealing with air, though, I kind of get the feeling pneumatics won't be the solution I'm looking for as my displacement would be a dozen milliliters at most. Or is it still appropriate? I have almost no experience with pneumatics. Could someone please lend some insight? What part am I looking for, and does a servo-controlled pneumatic pump exist? Because for the vast majority of the time, the pump will be off, and it will only take an upstroke and downstroke whenever the screen needs refreshing. Thanks, Brian Edit: And also, another reason why I want it to be something like servo-controlled is that I'd want to have variable amounts of displacement every cycle, depending on how many bubble on/off states are switching in that frame. The max displacement would only be going from all 25 bubbles completely off to on.