IS THERE ANY ALTERNATIVE TO KEYSHOT FOR RENDERING 3D CAD MODELS?
AFTER 3D CAD MODELLING THERE IS RENDERING
Lots. Photo shop, 360, really any rendering program will work. try autodesk.com you can get some nice programs for free in the educational area.
Also check some of the previous answers in the similar questions area here.
For Parametric modelling softwares Keyshot or Maxwell, both did their job well.
For polygon modelling vray, render man, Iray....