Depending on the computer system you have, you can use "Print to PDF" as the printer you want to print to; it opens a window as if you were to save it. If that isn't an option, downloading software is the way to go. CutePDF has worked in previous experience, and on a different computer I used a program called PDFwriter. After using both, neither of my computers have gotten any virus. I think one of them asks you to install a web browser, but if you read the installation wizard carefully, you can end up with only the program you need: no extra gimmicks. This is all through Pepakura, of course (I'm assuming you want to save your scaling, folds, and cuts from Pepakura Designer without having to pay for the full program?)
Personal preference of glue is hot glue.