Users can send out an invoice that is not associated with any inventory, and here's how to do it:

Under the Invoices tab, click on + New Invoice, then choose your invoice template.

Next, click on the Search for Contact button in the new invoice to select the contact you would like to send this invoice to. Next, click on + Add Custom Line Item and then on the edit button.

When you press the edit button, you can add the line item's description, price, and image if necessary and click on the Save button when you're done. You can always add more line items to this invoice!

Next, follow the usual steps to create a PDF by clicking on the Download PDF button in the top right corner or tapping the Send button to email it.