A pouch in five materials and two finishes is a catalogue. The same pouch with the customer's own design on it is a proof, a correction and a second proof by email, for every order. The configurator does that round in the browser: the file on the product, checked, priced and in the cart.

Web-to-print shops have had size, material and quantity pickers for years. What they could not do is show the customer's artwork on the finished item, or tell the customer the file is wrong before someone in prepress opens it.
So the order arrives, the file bounces, a proof goes out, a correction comes back, and the press waits. For a shop with no minimum quantity, that round costs more than the bag.
The uploaded PDF is checked automatically, by Enfocus in Lprint's case, and the customer sees the result on the spot: a pass with a report, or the error and what to fix. What reaches prepress has already passed.
Size, material, finish and add-ons on a 3D model of the real item, then the customer's PDF applied to it: glossy where it is glossy, transparent where it is transparent. The customer is looking at their own product with their own design on it.

A preflight runs on every upload. The customer gets the pass or the error at once and uploads again; prepress receives files that have already been through the check. The proof round shrinks to the cases that need a person.

The configurator lives inside the store, on WooCommerce, Shopify, PrestaShop or your own platform, reads the prices from it and hands back the configured order with the artwork attached. A draft can be saved under a link and picked up later, or by the colleague who has to approve it.

Nobody orders ten thousand bags of a design they have only seen flat on their own screen.
Show it on the bag, in their hand, and the order is easier to place than to question.

Every order is a different artwork on a different bag. Selling that by email meant a quote, a proof, a corrected file and a second proof before anything could print.
Send us one product family and the file spec you print from. You get a configurator that shows the customer's artwork on it, checks the file and hands the order to your shop.