I've noticed that there are several people who are unable to open .PDO or Pepakura files like this one: fav.me/d4drcfx
This is unfortunate for them, since there are many papercrafts which are only available as a .PDO file, such as the Twilight Princess Zelda model, which is fairly popular.
There is a bit of solution for those who are unable to open these .PDO files with Pepakura. I have a program (I don't remember where I got it from, but a google search should yield results) called "CutePDF Writer", which converts PDO. files into .PDF files. Though I don't think this'll work for people who are unable to open .PDO files, since this program works by opening the .PDO file with Pepakura, selecting print, then printing the .PDO file to the "CutePDF Writer" printer in the dropbox. After doing this you are asked for the location where you would like to send your converted .PDO to .PDF file.
My solution for people who want to make papercrafts available only in the .PDO format, but are unable to open these files, is to ask me to convert these .PDO files into .PDF ones for them. You just need to PM me a link to the papercraft you want me to convert, and then I'll upload the converted PDF file to a site like mediashare, or just send it directly to you via email or PM, whichever is best for you
I'll give you the .PDF version of any papercraft model you want me to convert from .PDO.
Just PM me.