Frequently, part of our jobs includes monthly invoicing for hourly labor. Currently, there is no way to bill for hourly labor based on employee time entered within D Tools. The solution for now is to export the time entries and create an invoice outside of D-Tools for all billable hourly labor associated with a job. Or to create a change order within the job for the time used, which still requires manually exporting the time report and adding to a change order. For a job that lasts over 12 months, this can result in a cumbersome amount of change orders to manage, which isn't ideal. Generally this is for Project Management time rather than technician labor. By being able to create an hourly invoice within D-Tools, it will keep all billing for a project within D-Tools instead of managing via multiple systems.
I'm not sure if it's exactly what you're looking for but if you just want to invoice for labor you can create a service ticket and bill through there, and when you make a service call you have the option to assign it under active projects.
So in theory you just create a service call, add labor, assign to your project, and invoice all through the service tab.