There are tutorials/patterns all over the internet. Here are a few:
|(Ignore my fat Slovak fingers)|
|Open, with the exterior showing|
|The inside and interior are lined with plaid Duct Tape|
|The library checkout cards form pockets to stash stuff behind, plus there's a clear plastic pocket OVER them, so you can slip something like your Drivers License (or public library card) into it!|
Next time, I plan to make one using the actual cover of a discarded paperback novel. The exterior would look like this:
I like how cheesy that cover is. Of course I'd remove the remains of that barcode label.