Oh, you're talking about "schmaltz" -- the Yiddish term for rendered chicken fat. I'm not Jewish, but I live in a community that is about 1/3rd Jewish, plus a lot of immigrants from Eastern Europe, so I'm pretty familiar with this and other food products from those cultures.
I've done this before, but because of concerns over cholesterol we don't eat in my house. Very easy to render it, just put the skins into a large kettle over low to medium heat, and let them render. They will bubble and pop at first, so be careful. As more of the water comes off as steam the popping will diminish. In the end, you should end up with clear, yellow oily fat and a lot of "cracklings" -- the crispy skin, much like fried pork rinds.
Its actually a great fat for frying or even to cook with as an ingredient, but most people now use vegetable oils for health reasons, although its kind of debatable whether or not this is for real, sometimes I think its just as healthy to eat the real thing, like real butter.
If you do a google search of "schmaltz" you'll find all kinds of websites about how to make it, how to use it, store it, purify it.
I don't know what kind of market there would be, or if you would need special equipment, licenses, or facilities to sell it.
