Is it permissible, Islamically, to sell custom-made products online (Instagram) by taking a down payment and receiving the remaining amount upon delivery after ensuring the item matches the description and is free of defects?

The transaction described is parallel Istisna', which involves concluding two separate contracts: one with the client and the other with the manufacturer. The profit is derived from the price difference between the two contracts. This has been permitted by a group of contemporary scholars and the Islamic Fiqh Academy. Among its conditions are: clarifying the type, kind, quantity, and specifications of the manufactured item, knowledge of the price, setting a delivery deadline, and the contract being binding on both parties once the conditions are met. It is not permissible to stipulate exemption from defects. The subject of Istisna' must be something that involves manufacturing and transforms it from its natural state. It is permissible to defer or pay the price in installments. The manufacturer is discharged upon delivery of the manufactured item, and the client has the right to reject the item if it does not conform to the specifications. It is also permissible for the institution, in its capacity as a client, to conclude an Istisna' contract with a manufacturer and then sell it to another party through a parallel Istisna' contract with the same specifications, provided there is no linkage between the two contracts.