this tutorial months ago.
This is how I make my ears for my Jak cosplays.
Sorry its all hand written. I only have a program called ArtRage and it doesn't have a text box option. So if you can't read my handwriting just ask if there is anything you cant understand.
I mentioned Worbla's Finest Art Thermoplastic in the tutorial, here's what it is and where I buy it from: www.coscraft.co.uk/3-plastics-…
I live in the UK so this is a UK site, but it wont take much Google searching to find out if it is sold near where you live.
I hope this helps with your huge cosplay ear needs!
It will work for pretty much any big eared characters.