Think about two contrasting products: one with which you are involved (e.g., a hobby, cars) and one you don't think about much when you purchase it (e.g., toothpaste, milk). How would you go about building community about a brand in one of the latter categories if you were the marketing manager?
In order to create a brand community in a more generic category I would begin by developing a product image. Even something as run of the mill as toothpaste can be individualized and given character. This is key to encouraging consumers to buy into the product and develop a loyal following. Initially I would begin with product design. I would determine if the product had unique identifying characteristics that distinguished itself. If so, these would be used to promote the brand. In the event none were present I would then pick a characteristic that might be common throughout the category but consumers might not be aware of it. "All-natural" might be used to describe a package of frozen vegetables. Of course, this could be said about other packages of frozen ...
This solution explains how to build a community about a brand in a category that is typically considered generic (toothpaste, milk, etc). Examples are given.