If you are just wanting to email an invoice to a customer, see this article.
If you are wanting to download an invoice to mail or to leave at a customer's door, see the remainder of the article below.
One Invoice at a time
There are many ways and places in the system where you can download invoices. If there is an action button somewhere in the system, chances are you can download an invoice from there.
Route->Process
If you want to download an invoice for a completed job, you will need to complete the job first. See instructions here.
Once the job is completed, you can download a completed invoice in the same manner as above from the route->process page. You can also do so from the following places:
Customer's Profile from Service or Invoice History
Financial->Unpaid Jobs
Route->Reminder->Action
This will download a non-completed invoice.
If you want to have your most common chemicals show up on a non-completed invoice, see this article.
Bulk Invoice Download
Route->View/Add
To download all invoices company-wide for a selected date range, see this article.