How do you maintain oxygen supplies for patients in hospitals in the developing world, where facilities are well below the standards we enjoy in the West? The Oxy Johnny breathe eezee mask is the latest innovation to take the developing world by storm. Built on the scuba principle, this simple DIY contraption uses just a condom and some bits and pieces to fulfil a life saving function. In some cases, the Oxy Johnny has made the difference between life and death. Here’s how to make one of your own.