If you are using the Online Store level of our Website+Marketing builder, you can use these instructions to add a product to the website.
If you have a lower tier, you can create an order form by using the "contact form" feature within the builder. You could then add the PayPal payment link for your customers to use. That said, this does not track any inventory or shipping options that the Online Store provides. You would have to manually link the submission with your internal order fulfillment.
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