These constellation viewers are pretty simple to make, once you've gathered your supplies. You'll need a Pringles can for each viewer you want to make (ideally, one for each student). I haven't found any good substitutions for this, but let me know if you do. Put the word out early that you're collecting the cans, and you'll probably make out just fine.
Use a large nail to punch a hole in the bottom of the can.
Then place the lid on the can (or the can on the lid, which may be easier, as pictured below), sandwiching the paper inside.
Hold the can up to the light and look through the hole in the bottom of the can to view your constellation. (Wish I could get a picture of what it looks like, but you'll just have to make one yourself).
You may want to write the name of each constellation on the back of the paper - that way you'll be able to see the name through the lid while it's inside:
Also, unless you're well-versed in constellations, you may want to draw in the lines of the constellation to help you identify what you're looking at.