Methods and devices for patterning electroless metals on a substrate are presented. An active catalyst layer on the substrate can be covered with a patterned mask and treated with a deactivating chemical reagent, which deactivates the catalyst layer not covered by the mask. Once the patterned mask is removed, the electroless metal layer can be placed to have a patterned electroless metals. Alternatively, a substrate can be coated with a blocking reagent in a pattern first to inhibit formation of the catalyst layer before a catalyst layer can be placed over the blocking agent layer and then electroless metal layer is placed on the catalyst layer. The pattern of the blocking reagent acts as a negative pattern of the final conductive line pattern.