I know what you're thinking, 'why bother?' but seriously, this project is so... easy, I bet you it's even quicker than driving down to the shop and buying one. There are a few major advantages too. Picking out the pattern, (most door snakes are just darn ugly) accomplishing something yourself whilst not having to cart the kids to the shop, creating a fun activity for your kids to do, saving money (these cost me around $1.50 each) and if you have odd sized doors you can custom fit them.
The kids filled them up with sand from the sandpit. They love the tactile procedure but most of all I think they enjoy the accomplishment.
Tadah! A bit nicer than your average doorsnake and just as effective! Maybe you've got 10 minutes to spare... or maybe you have doors that don't have a draft.