Get ready for your mind to be blown.
Place the router in the binder, and measure how much extra room you have.
Cut the flaps of the binder so it's shaped more like a book, but can completely cover the router. A piece of scrap fabric or paper can then be used to wrap the binder. Glue the fabric onto the inside flap, and then wrap and glue around until you reach the spine.
Fold and glue the fabric together on either side of the binder spine to create a more realistic spine. Continue glueing down the sides of the fabric onto the inside of the binder.
Once dry, write or print out your network name as the book title and your password as the author onto adhesive-backed paper. Stick this onto the spine for a discreet way of displaying your info!