Another idea for a piece with actual movement - inspired by Thing of the Addams Family and the Hand Box which, when you turn it on, has the lid raise slowly, a hand come out - flip the switch to OFF - and duck back in the box and the lid closes. Thanks to John Veerkamp over at WoodCentral for the suggestion.
Displaying lidded boxes is always a problem since, with the lid on, you can't see what's inside, and with the lid off you don't get the look of the parts together. This one would appear to let you see the two parts together, then begin to open so you could see inside. But just as you can begin to see what's inside - your presented with wriggling, writhing, unidentifiable THINGS, (gummy bear fishing lures) - and the lid snaps shut before ytou can figure out what you saw inside.
A small battery powered motor, a cam and pushrod, plus the lures - all that's left is deciding how to activate the motor - for one revolution of the cam.
This thing could appeal to that odd human characteristic - the enjoyment of getting the hell scared out of ourselves.
We humans certainly are an odd species.