Download the alien template, print, and cut out the pieces.
Make the alien's head by gluing the eye in the middle, just above the mouth.
Take the 2 antennae and glue them to the top and back of the alien's head.
Glue the completed head to the flap portion of the brown paper bag.
Place the belly in the middle of the alien's body and glue it in place.
Finish off the alien by gluing the body to the main portion of the brown paper bag.