Similar style business I believe. We don't sell the flooring to the customer box by box per say.

We sell 3000 sq. ft. installed for dollar amount and have labor and material costs and don't show itemized bills.

The only way I have figured out how to do this using inventory adjustments by adjusting qty on hand.

So I cut a PO to my vendor for say 20,000 sq. ft of flooring. We receive it and it shows up in my inventory.

Then on each job I adjust "qty on hand" and select the job I'm moving the inventory to. It works but becomes a little cumbersome.

Looking at Quickbooks online and I think you can do the same but you create a sales order with inventory items and basically sell them to the custom behind the scenes internally for zero dollar amount. Only way to get the costs showing on each job.