I finally got around to doing it! I tried to integrate the Mindstorms EV3 set (as much as I can) into the UCS R2 without changing the look of the R2. Only the lower half of the legs look different, but the rest of the set remains pretty much identical to the original UCS R2. Here's a vid of my testing out the IR function (i.e. remote control).

I'll probably add more functions in future (like the light sensor and pressure sensor, although I'm not sure where to put the latter). And adding a custom demo program with original R2 sounds! :D

That's a good idea! I never thought about that.

Was it hard to modify it like that?

At first I did not really notice the integrated motors, but when I dicovered them, they looked a bit ugly. Is there any way improving that?

The head spins a bit to fast though. Maybe trying to fix it with different sized gears would make it spin slower?

And maybe it is wise to make the connection of the head to the body stronger, it almost looks like a bobbing head

Nice job! As someone who has the Droid Developer Kit from the original Mindstorms theme, this brought back some fond memories.

The hardest part was actually finding a way to fit the motors into the original legs. The motor itself is about half a stud wider than the actual leg, even though the motor portion fits into the "feet" pretty nicely. I had to compromise design with functionality in the end, otherwise I'll have to actually modify the feet to make it wider and build a frame around the motor (which will give the R2 "thunder thighs" in a way, haha).

I'm using the remote for this, so I think the motors all run at max power, but if I use a program, I can control the strength of the spin of the head (and add sound effects!). I can probably look into using gears to tune it down though, but I'm no master builder, I'll need time to figure out how to do that ^_^;; Currently, the head is literally suspended by just the axle at the top of the dome (pointing downwards) which fits into the medium motor directly. That's also why it's a little like a bobble-head R2, with the head swaying around after it spins or when the R2 gets stuck when moving.

It can do with more mods, but so far, I'm liking it as it is :) Just need more time and parts...

very well done -- congratulation -- i know for a fact that this is not an easy ev3fication :)

Oh man, so awesome! 10225 is my favorite set in my entire collection...and this is fantastic.

I like it! This looks like a fun project, and I look forward to your updates.

Thanks for sharing. This looks like a fun project and something I have been planning to do, but just haven't got around to it. I have built my UCS R2-D2, but I have couple more that I plan on building and converting with motorization. I found this motorized version by Bart Lego on MOCPages http://www.mocpages.com/moc.php/397454, It does a great job hiding the motors and mainting the UCS look. but it lacks Mindstorms component.

I also have a EV3 set and I have some learning to do to see if I can integrate the EV3 brick with sensors and learn to program it. My ultimate goal is to have 2 droids, one as R2-D2 and other as R5-D4 and have them interact with each other, either by controller/Mindstorms brick. Should be an interesting MODing time. I'll update when I have something working. Wish me luck.