Everyone has plastic wrap in their kitchen, but if you have a large bowl you want to get in and out of frequently, or you'd like a bowl cover for a pot-luck or picnic, the answer may be as simple as a plastic shower cap with an elastic band. The elastic makes it perfect for all types of containers, especially large ones, they're reusable, and they're available in packs at your local dollar store (or are complimentary in just about every hotel room.)