I wrote here recently about how fake sketches allegedly by comic book and comic strip artists turn up a lot on eBay. Something else that gets forged is animation cels. They're frightfully easy to forge if you know just a little bit about the business.
Between about the mid-sixties and the time when everything went digital, the way animation art was created in American studios was as follows: The artist would do a pencil drawing. A technician would use a Xerox machine to transfer it to a piece of celluloid known as a "cel." An ink-and-paint person would flip the cel over and paint in the colors on the back. Once it dried, the cel could be laid over a background and photographed to create a frame or three of animation.
Once you have the basic pencil drawing, there's nothing difficult in the process if you have a Xerox machine, a supply of blank cels that can be run through it, a set of cel paints and a brush. You can buy all these things very easily.
Years ago, there was an artist who worked in both comic books and animation who was not well-liked. His ethics in those fields were about the same as when, to supplement his income — or to be his income when no one in those industries would hire him — he would manufacture fake cels and hawk them on eBay. In most cases, they were model sheets like the one above which he would paint and advertise as "production cels, used in the making of the cartoon series."
He started, of course, with model sheets. They aren't hard to come by. If you work in a cartoon studio, they're all over the place and animators who work for different companies have been known to swap Xeroxes. You can also find a lot of good ones online with a Google search.
He would transfer the model sheet image to a cel and then he (or his wife or someone) would paint the back. The cel, even though it was made in his garage, would be represented as having come from Hanna-Barbera or Disney or Warner Brothers or wherever.
He sold a lot of them online and at conventions and through other venues. When people bought directly from him, they didn't question the authenticity of his goods. After all, the fellow had worked in animation even if he hadn't necessarily worked at the studio that produced the show for which he was selling cels.
He was also selling legit comic book art and cels at the same time so that added to the credibility of all his goods. Some of the "real" stuff he sold had been obtained by swapping his cels to an art dealer for other goods. A lot of art dealers who should have known better wound up selling his bogus cels, as well. It's hard to tell the difference.
That's about all I have to say about this. The guy's not still around but a lot of his homemade Hanna-Barbera cels are. An animation art authority told me once that he guessed each cel cost the guy about fifty cents in material and about 3-5 minutes of labor. He sold them for anywhere from $20 to $100, depending on the complexity of the image and the gullibility of the buyer. Once in a while, a cel would miraculously be signed by Bill Hanna and/or Joe Barbera. Yeah, sure.
Be careful. It's a jungle out there.