What you'll need:
raw wool from a sheep. Any color is fine.
liquid dish soap
bowl of hot water
running water (a tap)
a piece of cloth or a straw placemat
What to do:
Take a handful of wool and gently pull it apart over and over until it is very fluffy.
Lay it out in a square on top of a kitchen counter or on the grass outside so that all the strands of wool are going the same direction.
Place another handful of wool on top of the first layer, but going the other direction - perpendicular to the first strands. Repeat with a third layer (going the same way as the first layer).
Now put a drop of liquid dish soap into your bowl of hot water. Pour about a cup of water over your felt. It should be really wet. Press the soapy water into the wool with your hands so it is all soggy and flat. Gently mush the felt around with your hands flat around and around until it feels like one piece of cloth. Then turn it over gently and mush the other side.
Squeeze out the hot soapy water and rinse your felt in running water.
Fulling your felt
Fulling is the next step in making felt. Put your felt on your placemat or cloth and rub it on the placemat. Give it a quarter turn and rub the other way; keep turning, and also turning your felt over, and keep rubbing. Then rinse and squeeze your felt one more time to get rid of the last of the soap.