Andy really enjoyed this activity. We're making lots more for Christmas presents. It's so great that Andy can make his own useful presents for his cousins.
Take some pure wool roving (can be purchased at your local yarn store) and a piece of soap and cover the soap with thin layers of roving alternating the direction of laying the fibers until the soap is covered with a few layers (about 3 or 4). It's fun to use different colours.
Slightly wet it with hot water so the fibers stick a little better to the soap then put it into a plastic bag making a knot near the soap to close the bag (I used a see-through small freezer bag - you could also use a zip lock bag). Doing this makes it much easier for kids because the fibers shifts a lot in the beginning before it starts felting and the bag helps keep it in place on the soap.
You then let your child rub it vigorously as much as they want. After doing this for a while I like to shock the fibers to help it felt easier so we took it out the bag and got a glass bowl of hot water. We then put the soap under a a running tap of cold water and then briefly dipped it in the hot water before placing it back into the bag to rub again. The sudden cold water wash shocks the fibers into locking tighter together as does the combination of rubbing (agitation), soap and warm water. Do this procedure a few time (about 3 or 4) until the felt is dense and to your satisfaction. Wash the 'foam' off with cold water and roll in a towel or some roller towel (kitchen paper towel) to get the excess water out and leave over night to dry.
Our dried soaps... (I like the way Andy arranged his soap to be purple on the top and bottom and green round the sides)
How to use: Wet it when bathing or showering and work up a bit of lather then rub on your skin as you would a cloth or sponge.