Anything that comes into my house of that thickness gets torn open/flat, the edges snipped off (and recycled), folded and sewn into a little pouch. Sewing the edges means that I don't have to use plastic tape.
Sometimes if I'm in a hurry, I'll staple the edges instead of sewing, but I've been warned by our post man to be careful with that since these packages are delivered by hand and we don't want to injure our mail carriers! As a philatelic nerd, I prefer to use real stamps instead of the post-office print-outs.
A few doodles make it a tad more special.