I'm at that wonderful stage where you spend most of your robot building days gently sanding. I learned a lot of lessons making Bender with styrene and wood. Bender was sanded down about a thousand times before he looked correct in my eyes. Hopefully some of those lessons will cut down the Bus Stop Robot sanding phase to half of that number.
One of the problems with sanding styrene is it is so darned thin. Very easy to go through if you're not careful. And once that happens .... repairs are not always easy. Also I learned to prepare the surface before applying any filler. Make sure all glue / construction adhesive is sanded off before applying any spot putty or bondo. Otherwise you'll never smooth the surface and have crisp lines.
The Bus Stop Robots have all their skin applied to the heads and torsos. So far so good. I started digging around in my junk boxes and found one really neat set of eyes (using 8 different parts) for the girl robot. To me, that's the fun part ... turning junk into something that people will look at and enjoy.
After the sanding and filling phase comes the bittersweet fun part .... applying paint. I say bittersweet because it's inevitable that once a coat of paint (or primer) is applied, the one million defects all of a sudden make their presence known. Ah ... just part of the process. But on the other hand paint transforms the project and that's when they will start looking like a robot