Complex Solids like the one shown here are created by using the Boolean operations of 3d Union, Subtract and Intersect. We show you how in our Autocad 3d courses.
Boolean operations were named after the English 19th century mathematician George Boole, creator of the sets and subsets of venn diagrams. The principles of Boolean operations are also used in computer programming and internet search engine algorithms.
In the example here the basic bracket on the left was created using the Box tool and punching in values for the three boxes’ dimensions. Then we’d go to the 3D Make panel on the top Ribbon bar. Select the three boxes and hit Union. The bracket is now one shape, illustrated by the fact that the lines dividing the original shapes disappear. Incidentally, this shape could also have been created by drawing a thick L-shape with the Polyline tool and using the Extrude tool to add depth. There are always a variety of ways to create your model in Autocad 3d – it’s just a matter of becoming familiar with them and choosing which suits you best.
To create the hole in the bottom box, we first need to create a Cylinder to use as the cutting object, like a cookie cutter. In order to align the Cylinder’s centre, first use the Line tool to draw a construction line diagonally across the top surface of the base. Then select the Cylinder tool and create a cylinder on top of the flat box to a certain radius and height. Note that in older versions of Autocad it may be necessary to drag on the bottom anchor point to extend the cutting shape below the box’s base. Go to the 3D Make panel > Subtraction. Click on the main object first (the Box) and hit Enter. Then click on the subtracting shape (the Cylinder) > Enter. You should now have a circular hole in the base. It’s good to switch to the Visual Style  panel (or type VS) > Realistic to see how it looks.
The groove on the underside and the sides were created in a similar fashion: first boxes were created which intersect the shape, then subtracted in the same way. The Intersect function can also be used to trim away parts of an object. And finally the Chamfer or Fillet tools can be used to finish off the edges or lines or circles, as in the example above.
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