As many index cards as you want pages.
Two pieces cardboard, thin enough to cut easily (see step 2 for information on the sizes you are going to need to cut it to)
3 Binder Rings (available from Staples in a pack, may be called "Book Rings")
Step 1: Punch Holes in Index Cards
The first time, punch the holes. The second time, use one card from the first time as a reference, so the holes will line up.
Step 2: Make the cardboard
NOTE: If you want a "cover" cardboard, cut another piece exactly the same size as the Index Card. Then punch holes in it just like the index card and use that for the cover.