See examples of tables of data that can be pulled in from Copper in the sync tables above.
Demo Docs
Invoice Approval Workflow with Copper
This doc lets you associate invoices from an outside platform with Won Opportunities, and track them through the approval, payment, and followup process.
Some companies give each project/job a unique identifying number, to aid in planning, expense tracking, billing, etc. This demo doc generates a serial number in a special format for any new Opportunities, and logs it into a custom field.