Felted fabric is created when the fibers of wool or acrylic are intertwined or matted, so they create a thick, dense fabric. Unlike knitted or woven fabric, it is not made up of woven stitches, so there is not a grain. Therefore, it will not unravel or fray when you cut it.
Use unspun wool roving, a felting needle, and a mat to needle felt a design or object. The felting needle has barbs along the sides, which catch onto the wool fibers and tangle them until the fibers become dense. You could make 3D sculpture, or a flat picture onto another piece of wool. Needle felting will not work if you use "superwash" wool roving (if it is superwash, it will be marked as such), because that type of wool has specifically been treated so it will not felt and therefore you can wash it in a washing machine. Beginners can use needle felting kits that come with wool, needles, a pad, and a pattern to get started.
Have you ever accidentally shrunk a sweater in the wash? The fibers in your sweater have felted themselves. When using a yarn made from an animal fiber such as wool or alpaca, the finished project can be shrunken or "felted" to create a thicker and smaller material. This process is technically called "fulling" and is executed by washing the item in hot then cold water while agitating. The easiest way to do this is in your own washing machine on the hot/cold setting. This can also be completed by hand to control the amount of felting and its location. Make sure to knit the project much larger than you want the finished project to be as some felting can be shrunken drastically.
Stiffened Felt- holds its shape and does not drape. It makes a nice background for a craft project, and can be propped up. It is easy to cut, paint on, or glue things to.
Adhesive Backed Felt- peel off the paper backing, and the back of it is sticky. Cut out shapes, and stick it to another surface. This type of felt is available in sheets, as well as die cut letters and shapes.
Wool - made from the wool fiber from a sheep. Not machine washable, but you can needle felt wool roving onto it. Brands that carry wool felt are National Nonwovens, Dimensions Feltworks, and Raggedy Junction.
Acrylic - made from synthetic fibers such as nylon, polyester, or acrylic. Also called craft felt. This type is very inexpensive, and great for a wide variety of craft projects.
For felt and felting tutorials and projects, visit ThinkCrafts.com