I REALLY like this idea. not just as a secret place, but also to utilize otherwise dead space

Tradewind Tiaras: Kitchen Renovation: How to Make a Secret Toekick Drawer

I have 16 linear feet of counter in my kitchen, plus a 4x3 island. I could easily add 60 square feet of storage space.

or at 3" high, that would make 15 cubic feet. That would be a pile 2-1/2 feet square.