Spare Fuse Holder
I keep spare fuses in my boat at all times you never know when one will blow. I keep then in a used film container, it is small and waterproof. These containers can be used for a lot of other things including weights, aspirins, hooks, toothpicks, and anything else you can come up with. They take up little space and if you drop them in the water they will float as long as the top is on.