Geared calling card
It's a geared calling card! Two slots in the top layer display different information as you turn the smaller gear, and a little window lets you watch the gears mesh.
Cut all three layers from card or bristol paper (nothing too thin). Glue all three layers together like a sandwich, using the small holes to line up the parts. Be sure to glue in the hubs of the gears, but not the gears themselves!