COGS Materials for a construction project and keeping track of how many of an item was purchased but it is not in our inventory..

My boss, a general contractor, refuses to keep track of inventory because he says everything bought is used specifically for a project. I have uploaded detailed Home Depot receipts into QBO. They automatically enter line items.  

Where I am hitting a road block is, we do not have inventory but I need to show how much of each item was purchased for the project. Meaning, its somewhat inventory because we buy it, but we immediately use it and by it only because that project needs it. Example: Egg Shell white paint. I noticed that the cost of this item for the project was extremely high for what it should have been (by looking at homedepot.com and writing down every time it was bought and took hours). The project was projected to use 50 5 gallon buckets of that paint. When I was done calculating everything by hand, I realized that 86 were purchased instead of 50. We found out the painter had was purchasing for a different project of his but using our money to supply the paint. The only way I can think to prevent this is by keeping "inventory" but only to keep track of how many of that item was purchased and nothing else. 

I know this sounds confusing but I am completely lost on how to do this because I don't want it as an asset, it will not be invoiced to anyone (we do lump-sum contracts only), and I will not be keeping track of how much is on hand AFTER the project is done. 

Is there a way to do this? Any suggestions other than a spreadsheet? PLEASE HELP! I'm desperate!