Combining fiber-reinforced composites with classic construction materials has tremendous potential for lightweight design but requires expensive equipment such as dies for injection molding. Additive manufacturing is cost-efficient for small volumes from fiber-reinforced materials. The MM3D (multi-material 3D printing) project analyses what technologies regarding interfaces, printer technology and identification of process parameters make economic fusion of 3D printing and established production processes possible. Results from pull-off tests suggest that adhesion between surfaces doubles with optimal substrate temperature and quadruples with appropriate plasma treatment. Because hybrid structures require printing on free forms, the authors employ a hexapod machine for rotational motion of an extruder head. The paper presents solutions for resulting challenges such as referencing pre-existing structures in the workspace, generating the printing path and coupling extrusion rate to printing speed. Finally, the identification of process parameters is addressed. Currently the technology is tested for manufacturing a nature inspired bike saddle.