Bowl of hot water
Variety of soaps
Pull the roving apart into small wisps. This is very important because if the pieces are large they will clump. Dip a piece in the water just enough to get it damp. Wrap the roving around the soap evenly. Repeat this until the soap is covered with several layers. When it looks pretty thick slowly and very gently start to rub the soap adding drips of really hot water. Soon it will feel firmly felted. We rinse in cold water and allow it to dry.
If you have a felting needle laying around you can felt a design in after it dries. Be sure to angle the needle so you don't chip the soap.
My son also sells his felted soap in his Etsy shop.