Fit the Brim Lining With the upper brim the correct shape and fit, set the brim lining underneath the upper brim and adjust it to fit snugly against the upper brim. Glue the brim lining overlap in place setting it slightly right or left of the upper brim seam, so that you don't get the hat too bulky with seams in any one area. Make sure the tabs for the brim lining are fitted up inside the tabs for the brim, and that all tabs are facing towards where the hat band will go. Gently run a round sided pen or pencil around the tabbed edge, to make sure the brim tabs create a curve, rather than a section of straight angles. If you still can't get a proper curve in the tabs, make some additional cuts into the tabbed area to allow the brim's tabbed edges to create a smoother curve. Do not cut below the tabs into the brim section.