I think magic lantern "slip" slides are really fun--a very simple early mechanical means of creating a changing image, with the black painted ground of the slide concealing (more of less) a second image that is revealed when the top pane of glass is pulled to the right. And I really love the bright blue bell in this one, which slides out to reveal a pretty blue belle!

Closed: 7 3/8" x 4" x 7/16". Good condition, with a bit of paint loss, as documented, which does not diminish the effect. Glass slides smoothly and easily and wood frame is sturdy.