What is the best way for exemple :
If one customer need to custom a T-shirt, ok he select the size etc.... and launch the designer, he finish him custom t-shirt and Add to cart, but how when the customer for exemple need 1, 5 or 10 or more T-shirt with the same design project ?
PPs simplicity aka not integrating things like these into PP.
that way it stays lean and very flexible across multiple shop platforms. most other design modules offer a vast amount of extra features, which turn out to be buggy or not supported with the various different shopping carts.