It's a popular question when Halloween costumes are being created but it's a question that even when it's not asked, needs attention. How do I stiffen fabric? The choices are almost endless. Interfacing is the first line of defense to stiffen fabric. Fabric bowls are created by a very thick, sturdy interfacing that makes the fabric free standing. In most clothing, light-weight interfacing is used just to give the fabric a little bit of body and shape in places like facings, cuffs and collars.
Halloween costumes are a creation... creations that usually need ingenuity to make the material do what you want it too. Foam backed fabric is not available everywhere, it may also not be available in the color you have in mind. Interfacing is a solution to get the fabric to stand or stay where you want it. Using fusible options make interfacing a relatively easy solution.