Years ago I first stored our Weber Q100 in a large contractor sized plastic garbage bag and when it wore out just replaced it with a new one.

Then I came across a large sports bag, put a Rubbermaid shoe tray inside for support, and voila - instant Weber Q bag.

Later I found this plastic storage bin, ironically with the exact shape of the Q.

Eventually wore it out so now I store our newer Q120 in this Rubbermaid bin and store it in the back of our Avalanche when it's not needed - out of sight, out of mind, away from "sticky fingers" who think they may like my Q as much as I do. ;)
