I carry my leads, DI box, Wireless, mains extension leads, set lists, plasters, pain killers, business cards, etc. in a tool bag I bought from B&Q for 18 quid. Has a rigid bottom, so doesn't fold up when you lift it, and a wide opening so it's not to hard to find stuff inside it, though it helps if I've remembered to put in what I'm looking for, of course!