Small Nesting Cup Pottery Rib

This is a pottery rib intended for a small nesting cup. There is a 1cm off set from the top to the bottom of the rib to account for the bottom fitting in the top. For the cups pictured I used 500g of clay and opened them to 6.5cm (using the rib to measure). Then I pull the height of the rib, a little over 9cm and opened to the rib. I have previously made my ribs from wood which take a lot longer and is generally less accurate.