How to Make Cat Ears
To make cat ears, start by drawing 2 equilateral triangles on a black piece of construction paper, making each side about 3 inches long. Then, draw a 1/2-inch thick rectangle connected to the bottom of each triangle. Next, cut out the ears with scissors, and fold the rectangles on the bottom of each triangle around a black headband. Finally, use tape or hot glue to attach the folded parts of the ears to the headband.
Gather your materials. For paper cat ears, you'll only need clear scotch tape, construction paper (one piece is enough), a ruler, scissors, and a headband. You can use glue instead of tape if you don't have clear tape. Use a headband that matches your hair color so that it blends in when you wear your costume. Draw your cat ears. Draw two equilateral triangles on your construction paper. 3 inch sides are a good size for these cat ears. After drawing your triangle, add ½” to the bottom. This will make it so you can wrap the bottom of the ears around your headband. Cut out your ears. Use your scissors to cut your cat ears out. Line them up together to make sure that they're equal sizes. Once you get them to be equal sizes, fold a crease along the bottom ½” up. Attach your ears to the headband. Place your headband in the crease of your cat ears so that it sits flat. If you're using tape, simply fold the ears around your headband and tape around them. If you're gluing them, glue along the crease of your ears on the inside of your headband. Hot glue will hold best for your cat ears. However, if you're using a plastic headband be careful not to burn through the plastic. Let them set. If you glued your ears, give them more than enough time to set. If you've taped them, you're ready to wear them! If you want to add something more to your ears, try cutting out white paper in a 1.5” equilateral triangle. Tape or glue this into the center of your ears. Gather your materials. For your furry cat ears, you need two clips, furry felt, cardboard, glue (a hot glue gun or fabric glue works best), a ruler, and scissors. Bobby pins are too skinny to work with, make sure to get some clips that are at least half an inch wide. You want to use flat clips, French clips, or an alligator clips. Cut your ears. You need to cut both the cardboard and the fabric for your ears. You can make triangular or oval ears—depending on what look you want to go for. For triangle ears, cut two equilateral triangles out of your cardboard. Cut your fabric. Wrap your fabric around the cardboard pieces to give you the shape you need. Mark a line where you wish to cut—mark it on the inside of the fabric. Add ½” to this outline and cut your fabric. Glue your fabric to the cardboard. Take your fabric and glue it around your cardboard ears. It will look best if you wrap the fabric over the top and glue at the base of your ear. Fold the bottom 1/2" inch at the back side of the triangle.  Glue your clips on the base of your ears. On the bottom of the back of your ears, hot glue your clips. Glue the ears to the top side of the clip—the bottom side will be against your head when you wear them. Let the glue dry and wear your ears. Once the glue dries, put your hair in pigtails. Place the clips above the elastics in a spot comfortable for your cat ears. 
Gather your materials. Draw your cat ears. Cut out your ears. Attach your ears to the headband. Let them set. Gather your materials. Cut your ears. Cut your fabric. Glue your fabric to the cardboard. Fold the bottom 1/2" inch at the back side of the triangle. Glue your clips on the base of your ears. Let the glue dry and wear your ears. 