Build a better mousetrap, so the saying goes, and the world will beat a path to your door. But is it true? There are over 4,500 mousetrap patents but this doesn't stop inventors coming up with new designs - even though the basic spring-loaded trap was designed in the nineteenth century and, you might think, is unimprovable. Jolyon Jenkins talks to people who dream of riches from mousetraps, and one who has even managed it. And he invents his own, ultra-humane, hi-tech trap. Will it impress the professionals? Presenter/Producer: Jolyon Jenkins.