The specific operation steps of making 3D renderings in CAD are as follows:

1. First, open CAD, and click the "2D Sketch and Labeling" option in the lower right corner.

2. Then click the "3D Modeling" option on this page.

3. Then click the "Southwest Isometric" option in the View menu.

4. Then click the "Concept" option in the "Rendering" menu.

5. Finally, on this page, click tools such as cuboid and stretching to draw a three-dimensional drawing with cad.