Large numbers of well-described components are essential for advanced synthetic biology and model-guided design of pathways and regulatory networks. Here a method is presented for the creation of libraries of novel control elements. From these libraries, parts with well-defined properties can be selected and used in construction of finely tuned synthetic systems. The example of the PFY1 promoter in S. cerevisiae is used to describe library creation using degenerate synthetic oligos and the circular polymerase extension cloning (CPEC) method. Additionally the workflow of screening the raw library for functional parts is included to provide a full overview of the process of creating and characterizing a component library for synthetic biology.