If you wish to make your felt Rhythm hat stiffer or floppier, it is suggested that you use steam from either a garment steamer (preferable) or an iron (using the steaming function).
HOW DO I MAKE MY HAT STIFFER?
To make your Rhythm hat sit more ridged, simply steam the under-brim of your hat and let it lay on a flat surface until dry. You can then also steam the top side of the brim and let is sit flat for a further period of time.
HOW DO I MAKE MY HAT FLOPPIER?
To make your Rhythm hat floppier, you will need to steam the brim of your hat on both sides. The brim can then be reshaped with your hands. Rest the hat by hanging it by its crown so the brim is not in contact with any surface. This will allow your hat to dry into the desired shape. You may repeat the process to achieve your preferred shape.