This was a cheap version of an artist's pantograph copying instrument. You pinned a sheet of paper to a drawing board, placed an original drawing/picture alongside and traced the pointer along the outlines of the original. The picture was reproduced on the sheet of drawing paper - albeit the lines being rather jerky in places. The Sketch-a-Graph was made out of black plastic and came folded in a long red box. I recall spending hours with my parents as a child touring the shops of Norwich to find one when they were all the rage.