Using the ALGOL language, Nees created drawings and graphics for production, art and architectural drawings. He wrote the new graphics libraries G1, G2 and G3 with ALGOL, for controlling the Z64 and random number generation. In 1965 Nees experimented with random numbers and circle arcs ("Kreisbögen"). The graphic "Kreisbogengewirre" (Arc confusion) was a graphic of this series, also known as "Locken". Frieder Nake explains how this graphic was created: ″In fact, the picture does consist of one continuous path of arcs. … The length and radius of the individual arcs are randomly chosen within the limits defined by the programmer … The picture in it present form is due to a fairly serious programming error … It was designed to be less complex and it had to be ended manually because of the error.″