Take a crocheted bowl made of wool yarn and put it through the hot washer cycle of your washing machine. Alternately, if you do not have a washing machine, submerge the bowl in a bucket of hot, soapy water.
Let the washing machine agitate the bowl; if you are using the soapy water method you will need to agitate it yourself. To do this, put on protective rubber gloves and submerge your hands in the water with the bowl, then scrub the bowl against the sides of the container and rub it together with your hands.
Remove the bowl from the washing machine or the soapy water when the fibers have felted. You will know the fibers have felted if you can no longer see the individual crochet stitches because they have fused together. The bowl material should resemble wool or felt fabric after this process.
Let the bowl air dry or put it through the dryer so that it is ready to use.
Get a wool or cotton crocheted bowl entirely wet by running it under the faucet or dipping it in a bucket or larger bowl of water.
Dip the bowl in a larger bowl full of liquid starch. If you use spray starch, spray the bowl thoroughly.
Squeeze out the excess starch and water from the bowl and use your hands to sculpt it into the shape you want the finished bowl to have.
Set the bowl off to the side to air dry completely. When it does, the starch will make it stiff so that it holds its shape.
Repeat this process and add more starch if the bowl is not stiff enough for your liking.