Antique lithograph stone?
Found this at a yard sale a few days ago and had to have it. It's a litho stone or some kind of stamp for the 1924 Lon Chaney film 'He who gets slapped'. Maybe for printing lobby cards? It's about 6'x8' and weighs 20+ lbs. Try as I might, I can't find another one like it or even similar to it online. I am hoping that someone here might know a little more about it. Thanks!
Not sure if the pic will show up here so if not, here's a link.
Here is a link that might be useful: