Using your thumb, push against your fingers in a pinching motion. This will thin the clay out to create the pot’s floor and walls. Do not try to thin the clay too much with one pinch. Instead, use a series of smaller pinches to work the clay upwards more than outwards as it thins.
Work to make the floor and walls as uniform in thickness as possible. This will help keep the pot from cracking as it dries or during firing.
