From what I've read, coofunkcurly will have an Arkham Asylum cowl ready soon if not now. You may want to get in touch with him. Or you could try out reevzfx. I know he's got an Asylum cowl too.
He also produced the New 52 Bats cowl, along with the Keaton Batman. Should be working on Returns.
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And I already make a Miller cowl
and you make the Batfleck cowl from BvS.