DesignNBuy has launched PrintCommerce as an extension for OpenCart
particularly about web-to-print product design tool to design various products like t-shirts, mugs, flags, shoes, buttons, pillow, iPhone case cover, bags and many more.
This tool is not use only to design online products but you can also get ready to print file which is easy to print on particular product. You can get free preview over here to know how it will be work and use to your online store.
Please refer depth in detail about DesignNBuy: PrintCommerce WebtoPrint Extension with video here