Souvenir, clothes and shoes retailers, publishing and printing businesses could use this service so that their clients can customize their business cards or create tailor-made note pads. Accessory shops can definitely use it as they offer a lot of possibly customized goods, such as mobile phone cases, watches, bags and thouthands more.
And of course food! There are some cases when a customer might be allergic to a certain product or just distaste it. With a product constructor you can easily create a combo of ingredients that will meet your personal taste.