You Need: A cake dome.
You Can Use: A salad-spinner bowl.

Even if you bake a layer cake about as often as Halley's comet swings by, you'll eventually need a cake cover. How better to preserve that buttercream still life you've created? Just invert the outer bowl of your salad spinner over the cake. To transport, put the cake on a large base and use masking tape to secure the dome.