These vases are made in two parts and glazed in three. I throw two large vases, dry them a little, then upend one onto the other, joining at the rim. I then cut a hole in the top (once a bottom!) and re-throw the rim. Below you can see a similar pot as it was thrown, and again as it was glazed.
It looks a state before the kiln magic happens. Pottery is a messy business!