1. Get yourself 3 legal size hanging file folders.
2. Cut one along the bottom fold. You will now have 2 long top sides
3. Cut one exactly in the middle of each side. You will have two
short top sides (b) and one short bottom piece (c).
4. Cut one along the wire hanger of each side. Remove the wire. You
will have one long bottom piece (d).
5. Get some wide tape (like clear packing tape).
6. Tape long top sides (a) to short bottom piece (c).
7. Tape short top sides (b) to long bottom piece (d).
I bought a box of 25 from Staples and used all of them -- works like
a charm! I line these with a split open 2 gal. ziplock bag to prevent
acid from the folders from getting into my paper.