Adding a custom / post message type to Woocommerce

I have a personal theme "A" and I want that it can also work without Woocommerce. When Woocommerce "WC" plugin is added I would integrate A products with WC. I have a custom post type called "objects", how can I make "object" buyable throught WC?

I've alredy seen this answer on StackOverflow Adding Custom Post Types to Woocommerce Where the solution in the end gives a free (not anymore) plugin to resolve.

I'd prefer to do this thing on my own, without helps of plugin. I'm curious and a pre-package solution isn't what i'm looking for.

We can try a easy thing .. you want a custom post type to store your products and when WooCommerce is integrated the added products in your custom post type can work as woocommerce products ..

1. Check if woocommerce is installed ot not.

2. If not, then Create a custom post type as 'product' (similar to woocommerce).

3. Add the custom fields similar to Woocommerce and add the products under that. (Image added for the custom fields with Woocommerce)
4. Now, add the products under custom post type , and when woocommerce will be added it will face a issue the custom post type already exist .
5. So if in future you want to add woocommerce to your site disable you register_post_Type function and install the WooCommerce.
6. All the products created in Custom post type will be visible in Woocommerce products options also

To check whether woocommerce is active or not use this code

<?php
    if ( class_exists( 'WooCommerce' ) ) {
      // code that requires WooCommerce
    } else {
      // you don't appear to have WooCommerce activated
    }
    ?>