A one-time product can be added directly in the funnel builder after it has been created in Payments → Products.
Navigate to Sites → Funnels.
Select the funnel you want to add the product to.

Open the Products tab.
Click + Add Product.
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Select your product and price from the drop-downs.
Choose whether the product is a Main product or a Bump product.
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Click Save.
Navigate to Overview and click Edit Page to enter the funnel builder.
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Add your section and row.
Add an element.
Select an Order Form element.
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Use the panel on the right to configure:
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