There are zipper pockets on both sides of the outside (I added 2 to mine, one on each side, one would probably be enough). It closes with a button and elastic.
Here you can kind of see how I constructed it. Both sides of the main piece (the part laying down on the couch) have 3 envelopes each for cash, and the piece I am holding in the picture has slots for credit cards on one side (last picture) and more envelopes on the other. Those could easily be interchangeable (i.e. both sides for credit cards (though if you are truly a Dave Ramsey fan, you probalby don't want to carry them anyway... my husband and are I cheaters!), or both envelopes, depending on how many you want to have. My wallet currently has 6 on the main piece (so if this is enough for you and you don't want credit card slots, you could omit the center all together) and 3 on the inner piece with 8 credit card slots.
As you can see, I goofed a bit on my measurements due to extra thickness with interfacing... so my inner piece is a smidgen wider than the outer piece, but I plan to fix that on any others that I do... As for labeling the envelopes, I've planned to either use fabric glue, little rectangles of muslin and a fabric marker, or possibly printing out my categories on fabric transfer paper... haven't really gotten around to that part yet...