I love this easy, money saving and eco-friendly idea. Dilute your hand soap and turn it into your own foam hand soap. Less soap down the drain, saves money, and saves on plastic since you will be buying fewer bottles of hand soap.
Take an empty foam soap container, fill it with with a mixture of your liquid hand soap (I am using my new found favorite, Peace Soap from Kiss My Face) and warm water. I have read varying amounts from 1:1 soap to water, to 1:4 soap to water, and even as little as just one Tablespoon soaps with the rest water. I would say find something that works for you, but leave at least 1/3 of the foam bottle empty for it to mix. Shake so it dissolves, and wash your hands!