sometimes called 'pise', (pronounced 'pee say')
This is a method of squishing the cob mix down onto your foundation by stepping on it. This pushes the cob into the spaces between the foundation stones.
Keep adding cob and compressing it together with your weight. When the sides start bulging out, get a friend to use their feet for a form.
Get your weight off the cob when it starts bulging out too much on the sides, technically called 'ooging'. Let the cob harden for a day or two, until it can support your weight. You can cut off the oog later with a big knife or spade, before it's hardened completely. If you like foot cobbing and have good balance, you can do it all the way to the top of the walls. Make the walls thick enough so you can come back and tidy them up by cutting off the rough, protruding cob with a machete or spade.