I have more t-shirt on my site with diferent color. In fancy product designer i created product with diferent t-shirt color. The problem appear when i want to remain same design on all t-shirt color. In this case must to create product with same design with diferent tshirt color. Is verry useful to select product design from individual product settings to remain same design on all t-shirt color for a product.
Sorry for bad english
you could use the "designs" tool for simply changing the base layer OR you can let your customer choose from different colors for the base layer. That way the product and all layers will remain.