Disclosed is a process for forming a conductor pattern on a face of a substrate, which is typically sorbing and porous, such as paper or cloth. The method comprises forming on the surface an exposed pattern of colloid particles, corresponding to the conductor pattern to be formed. The colloid particles suitable for use according to the invention are those that are capable of catalyzing electroless deposition of copper, silver, gold, and the like. After the exposed pattern of colloid particles is formed, precipitation of a metal substance on said face is caused, to form said conductor pattern.