Possibly an Early Thayer? 4 1/2" high x 3" wide x 4 1/2" long overall. This has the front and rear door that drops down like a Silk Cabby and has the bottom sliding load chamber, but only a hole in one side. This is used to vanish a silk.
Show the inside empty, close the doors and poke a silk into the hole, open doors and it's vanished. Or you can have a different colored silk or ball inside already. Poke a silk into the hole and when the doors are opened, it has changed color, or changed to a ball.