Add water, gizzards/hearts, turkey necks, and salt to a medium stock pot. Bring to a boil and reduce heat to achieve a slow rolling boil. Reduce liquid to approximately 2 cups.  Transfer broth to glass measuring cup. Melt butter in a medium sauce; whisk in flour and cook on medium low for 2 minutes to cook off the flour taste remove from the heat if it begins to turn too brown in color. (It should be light golden at most) Stream hot broth into the hot roux whisking constantly.  Bring to a boil and reduce heat.  Taste for seasoning.  If you plan to add last minute turkey drippings we suggest making a traditional roux which is equal parts flour to butter in which case you would use 3 tbsp butter and 3 tbsp flour.