This is fun.
Characters, of course, get animation model sheets. So do costume changes for those characters, even small ones. Bart Simpson. Bart Simpson with an Isotopes baseball cap. And so do props. That baseball cap if it’s picked up. Or the hat rack, if it needs to be a discreet object, separate from the painted background.
So back to G.I. Joe, you probably recall this exciting scene.
Animation color models are made the same way production cels are. A pencil drawing on one sheet of paper is run through a photocopier loaded with blank cel sheets. Out comes that drawing, now on a transparent cel. Detail:
I didn’t light this in such a way as to really sell it, but you can see the brush strokes. From the front (the top), cel paint color appears flat, because it’s flush with the plastic sheet. On the back (the underside), it looks a bit like peanut butter spread across bread. Oh, and the white bits on the red — that’s from the cel being stored against a sheet of paper for years, and then sticking to it, and pulling some paper fibers off when I separated the two. I’ve heard that putting cels-stuck-to-paper in an anti-static bag in the refrigerator can separate them better, but I’ve not tried it.
Also, while I’m musing, I’ll point out that in the screencaps above, there’s a glow effect on the control device. (Mattes!) I doubt there’s a second color model that denotes that color effect, but if this were a modern production, I wouldn’t be surprised if such a reference existed.
I have to say, even as a kid, I could not comprehend how an 8-direction joystick with two buttons could translate into articulated movements for a bipedal human. It was one of those times where the limitations of animation or animation design shook me out of my suspension of disbelief. I’m glad that Duke escaped, though.