Previous solution: https://invoicedragon.com/

HN discussion: https://news.ycombinator.com/item?id=36860898 (you'd have found this if you had searched HN for "invoice")

Or more recently, another invoice generator: https://easyinvoicepdf.com/?template=default

HN discussion: https://news.ycombinator.com/item?id=45884371