Creating a custom listing

Is there a specific way to create a customised listing such as pet portraits or should they just be listed in the same way as a ready made item and the details sorted out after the order has been placed?
Thanks
Roz

As far as I know there is no specific way , you can either list -sell then discuss . or… list asking people to discuss specific details/costs with you then make a listing for a deposit , then another for the balance.
All a bit clunky, but it works.