The MassFlix PDF mailers (sample) are pretty simple to use (hopefully!). After you've used them a couple times, you'll probably feel like a pro. :-)
Use standard 8.5"x11" paper. There's no thickness requirement, but thicker paper is preferred over thin copy-type paper.
The most important aspect is making sure you get them printed correctly, so that the size and relative position of different elements comes out right.
If you're using Adobe's PDF Reader, you should be all set, automatically. Unfortunately, most other PDF viewers don't honor the printing preferences embedded in our PDFs. So you will need to ensure that they are printed at actual size, and not reduced/scaled/fit to your printer margins! (Depending on how you're viewing the PDF, there should be a Print Scaling-type option that should be set to None, or Actual Size, or 100%, etc.; and nothing like Reduce, or Shrink, or Fit, etc.)
Once you've verified correct printing, you should be all set (or know what you need to do) for all future PDFs! :-)
To help verify correct printing, our PDFs have little indicators in 3 of the corners (labeled A/B/C). When printed at the correct size, the distance between A and B should be 10", and the distance between B and C should be 7.5".
If the PDF was printed reduced/scaled/fit to your printer margins (wrong!), it will be easy to tell: There are red dashes along the right and bottom edges of the PDF that will print away from the edges, as a result of fitting to printer margins. So if red dashes appear near the edges, you haven't printed correctly. (When printed correctly, those red dashes will get "chopped off" in the printer margins, which is normal, so they won't be seen – unless your printer has super tiny margins and can print to the edges, in which case they might appear right at the edge, which is fine.)
Note that some PDF viewers, while correctly printing at actual size (and passing verification), may print "off center." That is NOT a problem, but be aware that for best results you probably want all corner indicators (A/B/C) to be at least 5/16" from the edge (they are ~1/2" from edges by default).
Here's a picture of two mailers that have been printed wrong (red) and right (green) as indicated by the corners (click to view larger):
Now, after the printing is taken care of, let's walk through using the mailer!
Ready to go: with disc in sleeve, scissors for the 3 little snips, and glue to seal. We like the Elmer's glue sticks, but it's perfectly fine to use tape on the mailer instead. :-)
After cuts and folds (steps 1-4 on the mailer). It's important that the two bottom flaps on the mailer (formed by step 3) are folded/wrapped around the bottom of the sleeve, as shown. (The top of the sleeve should be at the top of the mailer; otherwise it doesn't matter which way it's facing.)
Ready to seal the top flap! Don't forget to glue or tape all the way over to the edge (blue). Also note the "scrap" area (marking for step 1a) will easily fold out of the way (yellow) by now after folding the bottom and top...
Ready to seal the side flap!
And done! Don't forget the stamp if you chose to use your own. :-)