Here is a quick demo of what he can do, from a long while ago before it got his metal skin on, so you can see inside. He demonstrates the 2-3-2 move towards the end.

To remote control the many dome panels servos, sounds and lights, I made an ATmega based controller named a MarcDuino and a remote control iPhone app called R2-Touch. The system became widely popular among R2 builders. The MarcDuinos are in continuous production and a team of programmer has taken on the further development of R2-Touch. Below is the first ever demo of the system - boy is that old! Look at that old iPhone. The control has since been updated to work with from the phone WiFi, although for crowded shows I still prefer to use the super reliable XBee link.

He follows the "club plans" which are on Many people contributed to the plans, and the club got sneak access to some of the real props, and finally, for the later Disney movies, official access to the Lucas archives so we could measure the real units and make them perfect. It has now come full circle, since the latest movies use R2 units built from club plans and parts. My own contribution to the plans was the model for the dome, which you can find here:

CuriousMarc dome plans
The build also uses many club parts. In particular the dome shape (derived originally from a film soundstage lamp reflector) is hard to make on your own. Mine is an older "spun" dome, made by pressing metal over a rotating form. The same process used to make trumpet horns.  The blue frame is also a club aluminum frame, which I modified for the 2-3-2 functionality.

A good R2 build seeks to advance the state of the hobby. One of my proudest achievements is the 2-3-2 mechanism, which is demonstrated below.

The side legs are actuated by linear actuators, while the center leg is on a custom build platform. It's harder than you think, as the robot is quite heavy, and the outer ankles have to change angle during the transition and lock in the correct position. The center leg elevator also takes a lot of weight and bumps when driving, and needs to be locked, which I achieved by including a magnetic brake in the drive. It took a good amount of machining to do the center elevator:

And as a 2-3-3 builder, you will eventually face plant your robot. Guaranteed. Part of the initiation ritual. Mine had a pretty spectacular fall at Maker Faire, which gave a good opportunity to make a video of the interior of the finished dome when I had to repair it in a hurry.

The power system consists of 3 LiPo batteries stuck in the back door. Can't put them in the middle since the center foot goes there when retracted!

The dome simply rotates on top of a lazy susan. I use a slip ring in the middle to power the dome, so it can rotate infinitely.

Getting all the door panels to work was a lot of work, but very satisfying when it all finally works. My daughter had a lot of fun with it.

I could go on and on and on, it has been such a long build. I'll try to post log updates when I work on something. Many more details on my web site and my astromech build log, in the project links.