Using this simple method, one can keep shaving razor blades sharp for many uses (around 150). This method is so far unexplained but according to my strong empirical evidence, works well! For a quick summary, check out the following video:
Amazingly, all you need is a smallish pyramid made from plastic. Our pyramid was obtained from a super market, and was initially used as packaging for Ferrero Rocher chocolates. It is shown in the images. This is a square based pyramid, not much bigger than your average Gillette shavers.