Given the season, I'd been thinking of an ice house. But I suppose that one could fill them with concrete, and stack them. Maybe scatter some small rocks betwee

Given the season, I'd been thinking of an ice house. But I suppose that one could fill them with concrete, and stack them. Maybe scatter some small rocks between layers, so they deform and ~interlock. And maybe even punch some rebar through them. But you'd need to cover the outside, to slow weathering. And stuff doesn't stick well to polyethylene. Gorilla glue does, so you could add a layer of foam, and then siding. I suspect that getting a construction permit would be iffy, though.