I unfortunately never got around to buying a pyrograuve, when I was doing plastics in the 70s I was still at school and the money I earnt working in the local newsagents after school and at weekends never quite stretched to the purchase of a pyrograuve. too much of my hard earnt cash was being allocated to LPs, discos, beer, cigarettes and girls. By the time I had surplus funds I was into lead. Nearest I ever got to a pyrograuve was a sharpened pin soldered to an old paint brush handle and heated up with either a candle or cigarette lighter.