Unfortunately it doesn't make money appearing from nothing, but as some of you already know the trick is in the way to introduce banknotes in that.
I'm sure that girls could be very attracted by your magic trick and they surely want to play with your (full of money) wallet! ;-)
Step 1: The project
I drew a simple 3D schematic to show you the way to connect the ribbons which keep the money. Notice that although in the 3D and in the animation you see a space between the two plates, in reality the ribbons are very tense and they keep the plates adjacent.
Here a 3D model ready to explore with Sketchup preview.
Step 2: The prototypes
I discovered that for euro banknotes a dimension of 80x100 mm is enough.
You can see the odd way the tape keeps the cardboard plates together, but it also lets the wallet opening.
Step 3: The (very) rough material
That solution good fits with the ribbons connection. Indeed we'll insert the ribbons ends between the two boards.
You can make this wallet from any rigid material, plastic, cardboard, thin metal, leather, etc.