If you've used the Zakeke 3D configurator React library to develop a custom 3D configurator interface for your store, you can apply it by going to your Shopify admin > Sales channels > Online store > Click on the the 3 dots button on the active theme > Edit code

From the code editor, open the file theme.liquid and add this code in the head:

You should assign to window.zakekeConfiguratorIframeUrl the url of where you've deployed your custom interface. That url must be a public one - it can't be a localhost one, and it shouldn't have any query string on it.