Brent Ross makes some of the best pneumatic mechanisms around. Check out this animated pirate he built last year. He was having a sale so I bought one of his lightweight lifters. Since I haven't learned to weld yet, I wanted to a have a professional armature model to copy once I get to that stage in my prop building. It's quite nice. The light lifter is engineered to operate a 20" travel from a starting point of 10" up to 30". I hooked it up to my compressor yesterday. It worked great straight out of the box and should provide a nice startle.