Is Zakat obligatory on profits from manufacturing custom-ordered furniture if savings do not reach the nisab at the end of the Hawl, and how is it calculated?

Contemporary scholars have differed regarding the obligation of Zakat on funds received through an Istisna' (manufacturing) contract, holding three opinions: no obligation on either the manufacturer or the procurer; obligation on the procurer for the price and on the manufacturer for the manufactured item; and the most preponderant view, which is that Zakat is obligatory on the manufacturer for the price received for the manufactured item, but not obligatory on the procurer for that price. The conditions for Zakat to be obligatory are that the funds reach the Nisab (minimum threshold) and a Hawl (one lunar year) passes over them. It is recommended to pay Zakat on all of it when the Nisab is met, to ease one's conscience and benefit the poor.