This felting technique is commonly called "Needle Felting"; it uses barbed needles to push fibres through the top fabric to lock into the base fabric. The more "needling" the firmer the effect. Usually the base fabric is wool although we have successfully used the technique on cottons that have a dense weave such as some of the good quality batiks. It can be used in many different fibre arts. It can be added to felted handbags (for example knitted bags that are felted using hot water to felt the fibres can have wonderful decorative touches by the use of a felting needle).
We also have bamboo mats that help with the wet felting technique. The wet felting method of feltmaking using water (rather than needles) to lock the fibres uses unspun wool fibres, hot water, soap or detergent, bubblewrap and a little pressure to create fabulously soft felt.