I'm just getting starting with models and figured I'd try the Silly Putty masking technique. I think it worked pretty well. I'm so happy with the result, I'm struggling with doing anything to it! The Silly Putty works really well, especially for complex designs. Just be careful what you use for paint. These are Tamiya arcylics applied wiith air brush, mostly! I painted the whole thing dark yellow, then masked off what I wanted to stay dark yellow and sprayed everthing that was exposed dark green. I then left the dark yellow covered and masked off what I want to stay green. Then I resprayed what was left exposed with dark yellow so I didn't have the dark green base under the red-brown when I sprayed it on. That's when I made my mistake. To save time, I sprayed the new dark yellow base from a can of Tamiya. Once that dried, I sprayed those areas with the red-brown. Once the paint dried, I started removing the Silly Putty, which was when I got my surprise--some chemical in the Tamiya spray can had started to liquify the Silly Putty. It was a real chore getting it all off. Fortunately, Silly Putty likes sticking together, and eventually I got it all off. I did the wheels with a brush, no masking there.
A couple things to keep in mind. Press the silly putty down really well. Whatever is exposed will get paint on it. I also had to do some touch up with a brush afterward, where lines weren't quite right or the Silly Putty wasn't pushed down well enough. Now, I'm getting ready to sand it smooth with really fine grit paper so there aren't any brush marks or paint edges for washes to settle into, which is the next part I'm still trying to make myself do. Here's the result:
