Don’t be fooled by the size. It’s home to 10 businesses. The Rainbow Market is a cooperative venture that opened two months ago at 644 S.E. Jackson St. in downtown Roseburg. The store is only 400 square feet, but that’s big enough for small displays from the co-op’s members. The focus of the market is food, and the options range from Asian lunch-to-go entrees to Mexican tamales, from artisan bread to gluten-free muffins and from cookies to frozen cuts of beef and lamb. There are also original watercolor paintings and dishes intended for use with the Asian cuisine. One of …