For extrusion based multi-material layered manufacturing (LM) processes, a CAD system has been developed which generates high quality toolpath for part fabrication. This closed loop CAD system includes solid model design & slicing, single-material toolpath generation, multi-material toolpath generation and virtual simulation modules. The solid model is sliced equally. Intelligent features and adaptive roadwidth optimum toolpath generation algorithm computes void sizes & their location and generates void free toolpath. The virtual simulation visualizes and validates the toolpath generated for the part. When the computed toolpath quality is acceptable, it is sent to the in house hardware Fused Deposition of Multiple Ceramics (FDMC) machine for fabrication.