DISK CUTTER OR MARKER
Disk cutters or markers are used to cut or mark circles of different diameters onto flat clay and can either be bought or handmade. You need a flat disk of wood, about 6cm in diameter, plus a thin bar of wood. It should be about 2 cm wide, but can be any length and should have holes drilled through it at the distances required.
One end is attached to the centre of the disk so that it can be moved round. Clay is rolled out and the disk is put on top. Push a narrow sharp instrument through the appropriate hole, and by rotating the arm you can cut or mark the circle.