I bought a 'wallet window'' (the plastic thingy that you stick in your wallet to hold photos and credit cards) from RiteAid. I looked all over town for that sucker! CVS, Target, Walgreen's, Claire's... finally found it at RiteAid - the last one on the shelf! Two per package. Now that I know what they are called, I can look online next time. Anyway, I cut off most of the part that is used to secure the window wallet in your wallet and then punched holes with a single-hole punch. If I do it again I would leave a little more plastic, I just eyeballed and had at it. Typical. A ruler could have been a good idea.
This photo, below, shows just how little I had leftover. Notice how close the holes are to the edge. Might tear at some point. Will then use my backup.
This is an open view, below, of the little staple-bound Leuchtterm address book that is visible in the wallet window in the first photo (black cover). It's so small it fits in one of the windows. Cool, huh? It only has my most critical phone numbers in it, family, AAA, etc. Just in case I lock my phone and keys in the car and have to borrow the phone inside my favorite Filofax store to call the tow truck. Not that that has ever happened.