My brain was sort of off and i used your little guy to jump-start it by making you an edit
So here's a suggestion on how to make the connections of the parts a bit more feasible as well as putting things into perspective. Just a small nudge here and there and the guy is suddenly more 3-dimensional.
On your previous version the cylinder shapes were much better i think. Starting from the edge with the brightest color makes them look flat.
For the yellow parts i used the brightest blue for extra highlight.
Also no need to save the black lineart, just go over whenever you need to. It just takes room in a small sprite for no reason.
Changing the design a bit wouldn't hurt either. Give it a hand for the other arm, maybe a three finger one, try and figure out how to make the other arm look more like bomb blaster. Like big holes that dump smoke when firing for extra cool effect and so on.