One I hadn't thought of ! I remember seeing mattes painted on glass in front of the camera when I worked for BBC TV Film Department (now sadly defunct), and they were astonishingly convincing.
I guess I would go for a website to do with painting where you might find someone who used to do this ? Of course, now, its all done with CGI but you would still need a ‘painter’ to create the artwork. If you look at the credits on anything recently animated there are reams of people creating backgrounds and what might loosely be described as ‘scenes’ !
Sorry I couldn’t be of more help.
