yup so i made one out of the box they gave him to me in!:D im sorry if you don't understand the steps. they're all in the wrong spots because i couldn't get pictures to upload and it wont let me move them. im not very good at explaining things either but i hope you would enjoy:)
leave the sewed areas out
one for each side and cut through the box too. hot glue a peice of plastic with three wholes punched in between them.
cut out the windows through the fabric and use the one extra inch ontop and rap it over the cardboard edges.
cover the flap with fabric.
rap the bottom like a present and do not hot glue the flaps.
make the straps(sorry i couldn't find the picture for how to make them anymore)