If you already have a bunch of product in your store and you want to add customizations to them, this article will be helpful for you.
The way Custom Product Builder works - it creates a full new product that will contain custom options, rather than adding them ti the existing products. However, it is possible to use Builder app with already existing products. If you are planning to do it you need to be extremely cautious about several things, that may affect your store.
Custom Product Builder works based on the Custom Type: cpb_product. If your product has this type it will be recognized as customizable and our app will run on the page of this product.
1.1. If your store is live, this means that all changes will be shown right away, and if your product is not finished on the admin panel - it will cause trouble to your customers - they will not see the correct price, won't be able to add the product to the cart, not all options will be available for them, etc.
1.2. Our app is running in its own interface, which is not connected to the templates that you created in your theme previously. So if you change the type to cpb_product, the interface of the product will be changed (for this specific product). You can customize the look of the product page using CSS code (You can also reach out to us and request assistance with the front-end adjustments), but if you didn't do it yet - that may ruin the user experience for your customers.
1.3. If you already using a custom type for the purpose of your collection, you can run builder in the Metafield method. Information can be found here.
Our Custom Product Builder app has a specific way of working with variants. In case you are using variants of the product for purposes of storing SKUs or you want to provide both simple options and advanced customizations from our app, you will have to keep the "Add to cart method" as Auto-generated variants. It allows you to have an infinite amount of variants, but this method has a couple of downsides. You can read about it here
Implementing custom options for different products.
If your products should have similar options you don't have to add them manually to each existing product. You need to create one product, that will contain all options. Then you need to download the JSON of this product on the Admin panel of our app. Settings -> General -> Import/Export product data -> Export -> Download JSON file.
Next, you need to open a new product, where you need to implement those custom options, by pressing on the product page -> More actions -> Custom product builder -> You will be redirected to the builder page, where you can upload JSON file in the same way. Settings -> General -> Import/Export product data -> Import. After that you can adjust new product - change images etc.
More information can be found here