There's a number of websites that let you design your own food online...
... Chocolate Bars: http://www.createmychocolate.com
... Ice Cream: http://www.ecreamery.com
... Nutrition Bars: http://www.elementbars.com and http://www.youbars.com
... Beef Jerky: http://www.slantshackjerky.com
What are some food products that you would _like_ to customize and why?