A super easy kid friendly way to make felt balls:
Fill a couple large pots with as hot water as you can stand it and dish soap.. Take some wool roving and wrap around to form a ball, dip into the hot water and then just place it back and forth from hand to hand without squeezing. AS it cools, dip it back in the hot water and keep forming with hands back and forth and dipping in water *this will shrink the wool into shape. Then you can add pieces of colored wool by wrapping around ball and repeat above process.
Let them dry and then to make sure they are truly felted, place in stocking (nylons) tie closed, and wash in washing machine in hot water, and then put in dryer.
Ours came out great!
Simple Living, Joyful Homemaking, Homeschooling Mom of 6