Download pepakura designer 3. You technically need a registration code but it still allows you to view, resize, and move pieces around. The only thing you can't do is save (which is where the registration code would come in) but other than that it's better than pepakura viewer. I would still get pepakura viewer though since there are some files (very few) that the scaling is locked by the person who model and/or unfolded them and can only be viewed.
