DIY Vintage Milk Crate Turned into Unique Ottoman Tutorial -- could use the plain wooden crates found at a craft store, plus thick or heavyweight fabric, foam, plywood. Could also add hinges to make the top open for storage inside!
By the way, I HATE the newest, cutsie, pretentious word - "up cycle" - you're being creative and reusing what would otherwise be called JUNK/TRASH! Repurpose / recycle - just call it that! Up-cycle is putting lipstick on a pig!