Get your cardboard box and cut three of the top flaps off the top leaving one there.
with the last flap write the name of your box onto it.
you can know glue the top flap to the box by getting a small peice of cardboard or paper and gluing it to both theflap and the box.
you can now thread a mouse through a hole in the top of the box and decorate the whole box.
thats all, know your kitty kitty has a nice little fun box.