Metamaterials are artificial, structured materials that offer fascinating optical properties. Within this thesis, we have developed a method for fabrication of three-dimensional metallic structures with sub-micrometer feature sizes. It combines direct laser writing (laser lithography) and electrochemical deposition. Thereby, we have realized helical optical metamaterials. They show a strong, broadband circular dichroism (chirality) and can be used as compact broadband circular polarizers.