This is the place to post questions and discussions on usage and style. The members of the Wordwizard Clubhouse will also often be able to help you to formulate that difficult letter.
We always called them shadow puppets but after looking that up, I see that shadow puppets were actually made from flat cut-out shapes. Wiki calls the hand shadows "shadowgraphy or ombromanie". I'm not sure how many people would recognize those terms.
"Hand shadows", "finger shadows" and trolley's "shadow puppets" are all used.
Signature: Phil White
Non sum felix lepus
trolley and Phil White : Thank you two so so much.
We used "shadow play" with "play" in this case meaning how kids play around.
WoZ on the wall
Signature: "The question is," said Alice, "whether you can make words mean so many different things."
WoZ : Thank you so much.