In TM3 you are able to print out an invoice.
To do this you will need to view an invoice. You can view or search for any invoice by going to Finances > Invoices. Either double click or select 'View' for the invoice you wish to print.
This will open up the invoice and at the top right hand corner you will see a button 'Print' which is highlighted in the image below.
When you click on 'Print' it will bring you to a print preview of your invoice where you can then check to make sure everything is correct before printing. Simply click 'Print' on the preview to print the invoice.