Die casting tools with improved cooling by conformal cooling produced using additive manufacturing allow to reduce cycle times and improve the part quality. Most available tooling materials for additive manufacturing are however, either not enough heat resistant or difficult to print. The paper presents Pearl®Micro TS700, an innovative 5% chromium, precipitation hardening tool steel, with a very good heat resistance close to 700°C and a good printability by laser melting for additive manufacturing of aluminum die casting tools. With different innovative heat treatments, the steel can be tweaked for highest heat resistance or better tenacity. Microstructures, hot hardness and temper resistance depending on heat treatment will be presented as well as impact toughness and tensile properties. Fabrication of hybrid tools will be discussed, where the part of the tool with the conformal cooling in contact with the cast part is printed onto a backing material to reduce printing time and material costs.