I had no idea a figurine of pic related existed and now that I've seen the 3A toy I want it really badly.

This is the first time I've ever looked into this kind of thing, so can you guys suggest other figures of robots with similar designs and exposed joints and pistons I can use as drawing reference?

I already use miniatures of other things and they're extremely useful.
Even things that are not strictly robots (e.g. excavator etc.) but have great movable joints would help a lot.