also, what material are you using for the pinhole? if you'r eusing the cardboard the box is made from you're going to have a hard time getting a 'sharp' image. I make mine out of aluminium 'coke' cans. Cut a can up with some scissors and make the hole by swiveling the needle (drilling) rather than punching it through, and like Gary says, sand each side with the finest sandpaper your can lay your hands on.