Take a headband, you already have and turn it into a cat ears headband!
I had this idea for a long time and now I thought, I'd give it a try. I don't know, if someone already posted something similar, but I want to make sure, that I wasn't copying anyone.
This is what you are going to need. You can find the ear pattern in the attachment.
First, cut out four black ear pieces and two white/beige ear pieces using the pattern.
You can cut the white pieces along the pattern line, but leave some space next to the line on the black pieces because you have to sew them together later.
Sew the white pieces on two of the black pieces. Watch out - they should not be identical ;)
Sew the black parts together. I sewed them on the inner side and then inverted the ear. Leave the bottom for stuffing.
Stuff the ears with a bit of cotton wool - not too much though!
Mark your headband where you want to have the ears. It is helpful, if you try it on in front of the mirror and hold the ears to look how they fit best.
Close the bottom parts of the ears by sewing.
Final part: sew on your ears where you marked the headband. Done! :)