a rotatable turntable tool is used in trimming wheel - thrown pottery . the turntable tool includes a base portion , a bearing member , and a cap portion which is rotatably attached to the base portion . a method of trimming an unfired clay workpiece includes steps of inverting the workpiece and placing it at a central portion of a wheel head on a potter &# 39 ; s wheel ; placing the turntable tool on top of a central portion of the inverted workpiece ; pressing downwardly on the cap portion of the turntable tool while rotating said wheel head to stabilize the workpiece , whereby the base portion of the turntable tool rotates with the workpiece , while the cap portion is substantially restrained from rotating ; and applying a trimming tool to an edge of the workpiece to remove unwanted clay therefrom .