R2 Steam Too
Here's my pitch for the next installment, J.J. Abrams: It's Star Wars meets the Industrial Revolution. It's Han Solo and Boba Fett playing chicken with a pair of choo choo trains. It's a steam-powered R2D2. R2 Steam Too! I even have a prototype of that last one, courtesy of CrabFu and I-Wei Huang.
Huang set off on his first robot-building endeavor when he was 5 years old; it was an R2D2 made of LEGOs. Later in life, as he began tinkering with steam and creating a host of nifty steam-powered contraptions, it made nothing but sense to inject the vaporized water into one of his fondest childhood memories. R2 Steam Too began as a broken Hasbro R2D2 Interactive Droid, which Huang won cheaply from an Ebay auction. After stripping the toy down to its shell, he added a shaft and exterior sprockets, followed by dual steam engines with chains to power the sprockets.
An old Cheddar model, slim enough to fit inside the body with adequate layers of sheet metal and fiberglass insulation, serves as R2's boiler. Engines are a pair of Wlesco marine units whose steam supply is split with heat-resistant silicone tubing. To function, the robot's steam pressure must reach 20 psi--a level that allows for a fairly short scamper across the floor. Gearing is also very low, so "scamper" may be a little generous. R2S2 kind of moves slower than a one-legged dog on tranquilizers. But even so, Huang points out, he is still the fastest steam-powered R2 in any galaxy of the universe.