Currently, we don’t have a feature to pre-populate a form with cart content to be sent as an invoice request.
It sounds like our Free Orderes feature might work here though.
With Free Orders users can go through the checkout flow without entering card information. The user will then receive an email with their order information. Afterward you can follow-up with the user and send an invoice or quote for their order. You can then collect payment outside of Webflow.
To use our Free Orders features simply set the price of the product to $0.00. At checkout the user will only need to fill in their email and billing address.
Keep in mind that an Ecommerce site plan is required to use this feature and a Stripe or PayPal payment gateway will need to be connected.
More information on Free Orders can be found here: Accept Ecommerce orders without payment | Webflow University.