So I have 20 type of t-shirts and they have different prices.
Sofar what I did I created a woocommerce product for each tshirts and connect it to the appropriate product in fancy product designer.
I would like the customer to be able to switch the product in the designer.
If you want to offer multiple products in one designer, you have to create multiple Fancy Products and assign these to a single product designer for a single woocommerce product.
You can not assign 20 woocommerce products to the product designer.