This is a great question, @PLAEUSA,
Having the option to create columns with calculated formulas in QuickBooks Desktop is a good suggestion to add in our program. Currently, the columns on estimates are read-only fields.
As a workaround, you can venture other third-party estimate processing applications that handles this type of customization. Visit our app store to find the best tool for you.
We also have a separate forum for Intuit Developers where you can find engineers who can help suggest third-party apps and program integrations. Here's the link to the website: Intuit Developers Community.
Your suggestion is important for us so we can make our products and services better. If you have any questions with QuickBooks, feel free to connect with me any time. I'll be right here to help. Have a nice day.