Fyi,
Have a look at this post for Blender Cycles & Blender Internal setups for flat shaded 3D models:
https://blenderartists.org/t/flat-no-shading-colors/689942/2
Be aware Blender Internal will disppear in future Blender versions. Blender Eevee will certainly have a similar solution/node setup as Cycles for flat shaded rendering.
Pieter