A typical case where a customized product interface is required would be a site that makes items such as curtains and blinds. Both height and width could be any value (in centimetres) between perhaps 50 and 300, so it becomes impractical to create every possible width or height as an option. Furthermore, although options can have a price modifier associated with them, this doesn't really help with pricing where width and height are both variable.

Instead, a far more manageable solution would be for pricing to be obtained from a lookup table or a formula.

Situations where a highly customized product interface is also required or where a client side configuration system has already been created may lend themselves to custom product controls. For example, a client side tool that lets you design a t-shirt and add text and/or images, then buy the item.