Thanks for the words of encouragement all, sometimes I feel like I get stuck in a rut but it's so much fun when I get back into it.
There's also a reason why the thread isn't "R2-D2 build" and that's because my girls chose the colour, a really dark purple which we grabbed a can of today and put the first coat on. (Panels just placed on for show)
Otherwise I've been working on a second arm and filling more on the first. Got some paint onto parts that are meant to be metal (primer then aluminium on the front lower vents and coin slots). Really want to get the dome painted silver as well, but I've only just cut free the lower ring above the bottom ring. Soon. I'm also so far keeping it all with dupli-colour. Purple is a paint/primer which seemed to go on oaky (I think I'll still want to hit it with some sandpaper before more coats) but the straight primer is really really nice.