Adding a chamfer or fillet to the edges of a 3d object adds realism to the model. This is one of the many topics we cover in our Autocad 3d courses. 
The bracket object shown here was created using a combination of Boolean operations: Union, Subtraction and Intersection tools. We cover these subjects in another blog post.
To chamfer the edges select the Chamfer tool > select the lines which make up the edges you want to chamfer, and hit Enter > type in 2 for the distance, and hit Enter twice. Then click the line or lines again > and Enter.
Using the Fillet tool follows a similar procedure – in this case the top edge was filleted with a radius of 2mm.
On small objects like this a chamfer or fillet can add a sense of realism to your model, especially after you add realistic lighting, since they catch the highlights, adding to the illusion. But for larger models like architectural or interior design models, it’s not recommended since this will increase the file size and rendering time. You could, however, chamfer or fillet the edges closest to the camera, and leave the other edges as built.
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