A Way to Calculate Deposit Amount from Line Items in Estimate

Does anyone know of a way to calculate the deposit from the line items in an estimate, and have that deposit mentioned in the estimate message? For instance, as far as we know, the only thing that can be stated in the estimate message is a percentage that is due for the deposit. It would be nice if items could be marked for “deposit” as they are entered into the estimate, so that when the estimate is complete, the deposit amount could be listed in the estimate message. In our old quoting system, there was a check box for each line item, and when it was checked, that item’s price was included in the “deposit required.”
Thanks for reading and commenting! Blessings!