I use the very stiff pellon, either fusible or plain. Also a stiff product to use is decorator craft interfacing. It's good for table runners and totes to give body but not rigid stiff.
One tip I learned in a purse making class. Fuse a thin interfacing to the fabric before using the fusible stiff interfacing. It will prevent the wrinkles and puckers you sometime get with the fusible that show up on the fabric.