Alternately, you can cut out a small hole here wide enough for your finger and use that as your tongue.
For animal puppets of reptiles and fish, use cutouts from various colors of construction paper to create multicolored scales. For birds, make cutouts of feathers from construction paper. Glue them to the bag in layers, starting at the bottom of the bag, with each added row slightly overlapping the one underneath it for a more textured effect.
For the upper row, add a half-inch of extra space along the top. Once you cut it out, apply glue along the top with your cutout facing up. Then stick it underneath the bottom of the flap. For the bottom row, apply glue to the back of the cutout. Fix it to the body of the bag. As desired, either fit it in place so the upper row and bottom row meet when the mouth is closed, or hide it underneath the upper row and the bottom of the flap to create an overbite.
Use yarn to make mustaches and beards as well. For spiky or crazier hair, use colored pipe cleaners instead. For animal puppets of mammals, use layers of yarn to create fur. Cut strips of desired length and glue them to the body of the bag. Start your first row along the bottom of the bag rather than the top in order to avoid having to lift layers of yarn to glue underneath them, which might make a mess. Use colored pipe cleaners for whiskers.
Since the legs will dangle out of the opening, be gentle with your hand as you slip it in or out of the puppet.
To manipulate the arms, trace a second cutout for each arm once you’ve cut out the first: a front-side and a back-side. Glue the two together, leaving a small gap at or below the wrist. Fold the arm where its elbow should be to create a crease. Then insert the thin end of a chopstick (or a similarly long and tapered object, like a sharpened pencil) into the gap by the wrist. Manipulate the chopstick to bend and extend the arm. For bird puppets, use the same method to create wings. For fish puppets, use the same method to create lateral fins.
For a more durable tail, trace your first cutout on more construction paper or cardboard to create a second cutout. Glue the two together except for the extra length at the end where they will meet the body. Then crease the extra lengths in opposite directions, apply glue to each, and fix the tail to the back of the body. For fish puppets, use the same method to create a dorsal fin.