The Ruling on the Contract of Istisna'

A man has a shop for selling furniture. Sometimes a customer comes to him and requests a custom-made seating area, so he needs to go to another city to have it made for him. Then they agree on the price, and he may even receive a deposit before going to have it made! What is your opinion?
Yes, there is nothing wrong with this; because he has not sold him a specific item, rather he has agreed with him to manufacture a specific item.So the correct view is: There is nothing wrong with it, and there is no obstacle in it. This becomes a debt in his liability, and he acts according to the terms of the contract.