A certain amount of 3d modeling in Autocad can be done by simply adding objects together, as seen in the screenshot here. This was created simply using the solid objects found in the 3d tools menu, all of which we explore in our Autocad 3d courses.
Create this collection of objects using the basic shapes tools. Note that the base plate has a depth of  minus 10. This can be useful when building the objects on top since by default objects are created on the X-Y plane. Note that many of the 2D drawing tools can be used in the 3D environment. For example, to centre the Cylinder on top of the Cube it will be necessary to use the Line tool to establish the centre point, by drawing from corner to corner of the Cube.You could also use Snap and Grid settings of 10mm for this exercise.
If you later need to reorient the grid, type UCS > W. Use the Move tool to move objects into place when necessary. Use the Mirror tool to copy the Cones. Use the Copy tool to copy the Cylinders. Use the Chamfer and Fillet tools. As you build, experiment with the various Visual Styles and 3D Navigation controls.  Apply the standard isometric views found in the drop-down menu.  Use the Constrained Orbit tool to rotate around the model, or press Shift and the mouse-wheel. Press and drag the mouse-wheel to pan, and roll the mouse-wheel to zoom in and out.
The 3d interface in Autocad is user-friendly and easy to learn, and we take time to teach a broad range of applications in our classes including modeling, materials, lighting and animation. See many examples of our clients’ work on our Facebook page. For more information there are lots of resources on the web, but try the Autodesk site to begin with: www.autodesk.com. Support options and user forums are also available from the home page.
Other related Autocad 3d Blog Posts:

• Autocad 3d introduction
• Autocad 3d modeling
• Autocad 3d blocks
• Autocad 3d commands
• Autocad 3d basics