The Force is strong with Instructables user The Papier Boy. Includes freaking-out R2 unit!
The spinning droid was constructed of Styrofoam and painted to look like R2-D2. I used one of my daughter’s old toys to create the motion. The toy had a gear on it that spun when a button was pushed. I cut the toy in half (it was too big) and mounted the toy to the underside of the body and glued the droid head onto the gear. To control the spinning I used an old NES controller. I re-routed the toy’s switch through the NES controller so when the A or B buttons were pushed the droid would spin for about 15 seconds. For audio, I downloaded some R2-D2 sound effects from a website and used Pinnacle movie studio software to string them all together into a 50 second babbling droid Mp3. I loaded this onto an iPod and connected it to a small portable speaker system that I hid inside the body of the car. This way, each time I started down the hill, I could push the NES controller button and the iPod play button to commence the droid freak-out.
[via Dude Craft]