Do some 3D Modelling

Modification on a CAD file design to produce a new file for cnc router cutter. The project is to study 2 designs of a model helicopter main frames from photos and make one new set with the best parts of them.. I have a cad file of the original design of the main frames for reference of actual measurements and a photos from the 2 others.. I want make a new frame set with the best sections of two others designs..