Old Holgate nesting/stacking boxes are among the things I stalk, though I've only ever scored one set, and I think whoever out there has some is never letting them go. There are a few different sizes and varieties that were made, all highly covetable, but I have never seen another set like this: inside the walls of each of the boxes are what I'd guess are tiny metal balls, which make a rattle, with the pitch graduated from highest for the smallest (green) box to deepest for the largest, red. Pretty great.

Red box measures 4" w x 4" d x 2 7/8" t. Green measures 2 5/16" w" x 2 5/16" d x 1 13/16" t. Plenty of dings and some paint loss as pictured, but still great looking and I quite indestructible I believe.