When you buy custom parts for a customer, there are some issues.  This is from my answer in the QB help forum concerning custom auto parts – but the concept holds for anything.

First understand that using a non-inventory item will send the expense to the COGS account (or what ever expense account you select) when you buy the item.

Then you need to create the non-inventory item with enough flexibility so that you are not filling your item list with what will be rarely used items.

1. Create a non-inventory item called custom part and click the check mark to make it used in assemblies or to be sold, select a sales account.

2. Use Enter bills to buy the part, on the item tab select the custom part item, in the description block enter a real description of what you are buying … i.e. tuck and roll headliner, Hurst shifter, etc

2a. enter the cost
2b. Select the customer.
2c. check mark billable.
2d. pay the bill
2e. This send the cost to the expense account (COGS)

3. Select create invoice

3a. Select the customer and a pop up window will come up asking if you want to select the billable items to be added – say yes.
3b. On the pop up window click the items tab, select the items to be added
3c That puts the cost and the item on the invoice – change the cost to the sales price on the invoice.
3d. mark the invoice as pending if this is a continuing project, or save the invoice.

When the invoice is saved the sales price on the invoice goes to the sales account.

I don’t know of a way to get an automatic markup, and don’t see a way to get this on a sales order – but I don’t work with this scenario much at all in my business so there might be a way.

When you create the non-inventory item, I purposely left the descriptions blank, that way you can enter what you want on the bill or invoice without having to delete what is already there.

You might consider using several non-inventory items with generic titles to group expenses, ie

Custom Mechanical
Custom Upholstery
Custom Audio
etc etc