If you're looking for a cheap, DIY alternative to shelling out cash for a replacement lens hood, look no further than lenshoods.co.uk. They offer free PDFs with rounded and petal lens hood designs for plenty of lenses from Canon, Nikon, Olympus, Pentax, Sigma, Tamron and Tokina. Of course, they recommend printing on a darker, more rigid material than plain white paper if you can. But if you've already got a printer and the paper, you certainly don't have much to lose giving it a shot.