Istishna’a:

 Istishna’a:   

“Istishna’a is a contract between a manufacturer/seller and a buyer under which the manufacturer /seller sells specific product(s) after having manufactured, permissible under Islamic Shariah and Law of the Country after having manufactured at an agreed price payablein advance orby installments within a fixed period or on/within a fixed future date onthe basis of the order placed by the buyer. 
AAOIFI says  “Istishna’a is a conract of sale of specefic items to be manufactured or constructed, with an obligation on the part of the manufacturer or builder (contractor) to deliver them to the customer upon completion.”

In “Istishna’a contract, the buyer is called ‘Al-sani’ and the goods or the subject matter of the contract ‘Al-masnoo’