Paper lunch sacks. Markers. Clothespins. Ribbon. Stuff to put inside. That's it, assuming you have a wall to display it on.
Sketch your numbers on the bags. No need to be fancy, though I drew mine in block letters, added white and gold decoration, and made the numbers 3-dimensional with the black marker. Forgive me for flaunting my art background.
Tack up your ribbon onto the wall. I used nails, but you could probably use those hooks that stick to the wall and easily come off when you want them to. Then arrange your bags, pinning them with clothespins.
Once each bag has been opened (I plan to reuse them again next year; plus they're easy to store flat), we'll put the holiday cards we receive on that wall in place of the bags.
(p.s. if you're wondering about those lights, they came from Target a few years ago, from their patio section)