Rheingold3D you all the tools on hand to create high quality and accurate industrial 3D models.
You can either work with Bezier Splines and Shapes or build your model from one of the build in solids.
If you have sketches or blue prints on hand, just load them as background images into Rheingold3D.
Final rendering can be done with one of the integrated rendering engines or just export your model to your favorite 3d application.
Please notes that all tb-software products can also export 3d scenes to STL or even IGES file formats.