You can ship to the USA only if that's what you prefer. You would just check off the US in your listings but you also have to go to the buyer requirements page to check off ' Block buyers with a primary address in a country that I don't ship to. Are you drop shipping from the US? If you are shipping from Sri Lanka, I don't understand why you want to ship only to the US. https://www.ebay.com/bmgt/buyerrequirements
I don't know what you mean by a custom base.
