In traditional electro discharge machining (EDM) the usual practice is to form a 3D female cavity in the work piece by making a corresponding male shaped tool and plunging this into the work piece. Recently, however, computer numerical control (CNC) EDM machines have become available which have the potential to generate a detailed shape without using complex electrodes. This paper describes a novel method of electro discharge machining which makes the generation of linear, circular and curved contours possible without any special electrodes. The experimental work employs CNC EDM, mild steel work pieces and inexpensive ''frame type'' copper tools. The results indicate, relative to the cavities produced, an improved effective material removal rate (MRR), a better surface finish and a lower powered machine. The paper also introduces the effect of EDM parameters on the process performance by modelling and analysing the experimental results using statistical techniques. Finally, a few applications are discussed.