Build CAD software

I want to build cad software. I want my software to look and function like Blender. Blender is a free cad software available at blender.org. ProgeCAD Smart! is another good free cad software to simulate besides Blender but Blender is my first choice. Obviously I want my own branding as well as a few back-end customizations. However I need all of blender's functionality. I don't care what language or platform you use. Note: This is one of 4 software I wish to build. The other software include mid to high end business accounting software, security testing software (like CORE Impact Pro), 3d computer graphics applications (like Softimage Face Robot or Rederware SDK) and 3d game engine (like Source Engine). If any of these seem easier to build, please let me know and the bid can be for developing one of these other types of software.