Once upon a time, there was no getting around paper. Retailers would fill out and send purchase orders to their suppliers. The suppliers would process the order, fill out an invoice to mail to the retailer, and record the transaction in a manifest. These days there are more efficient options.
The pencil-paper-and-post transaction was unwieldy, time-consuming and ripe for copying-errors that could result in shipping the wrong product at the wrong quantity at the wrong price to the wrong place and a month late.
Computers, evidently, haven’t made things a lot better for many smaller businesses. For example, a 2015 survey of 200 companies showed that 50 % receive most of their invoices as a piece of paper sent through the postal service.
That data entry and filing work might be manageable for doing business with a stable list of small trading partners. But it might not get you anywhere when the opportunity to sell through big box retailers arises. For that, you will likely need to use EDI. What does EDI stand for? It stands for Electronic Data Interchange.