I've bought and sold a lot of carved whimsies, so increasingly it is unusual ones that draw me. I've not seen another like this, with squarish sliding form rather than a ball inside the "cage." I really like the clean geometry of it, and it makes a pretty satisfying clack as the sliding piece hits the top or bottom top. One can also get the sliding piece to stay in place mid-way up.

5 7/8” t x 2 1/8 x 2” and in very good condition. Definitely with some age to it but I don't think antique, maybe mid-century.  Of a nice scale -- more like tabletop sculpture than a little carving.