After much-faceted changes, the period of Structures called the Marcostructures (enlarged elements) slowly changes at the beginning of the 1970s, as Zdeněk Sýkora´s attention is attracted by the line emerging on the interface of the black and white areas. In 1973 the lines become an element of his new paintings for the first time. Unlike the structures, he abandons the strict order and utilizes randomness to create paintings with lines. Shapes, lengths, thicknesses, colours and their crossings are determined by random numbers generated by a computer. 
Simultaneously with his studio works, he still paints in the nature.