You can now build your own lock to's in the Maintenance section.  You can name it and add variables to multiply against each other.  The 'multiply by' and 'divide by' options are still available for each department item if you need to use a numeric value

Maintenance > Orders > Department Items > Quantity Formulas

Enter the name you want for the 'Lock To'

Select an option from the drop-down, select {Add Variable}

Once all the variables are added, select {Save}.

e.g. to calculate total impression to charge ink: Impressions = Press Sheets x Passes x All Inks

        to calculate square footage of finished quantity, to charge chipboard by square foot per pad: Finished Size - Square Feet x Quantity

        to calculate total sheets for a multipart job to charge NCR gluing per finished sheet: Multipart = Press Sheets x Ons