Using AutoCAD to create a 2D drawing - while not exactly easy - is done using the same mind set that you would use while drafting on the board. But with the advent of computer aided drafting, and creating 3D drawings for production and problem solving, AutoCAD provides options that do not have specific counterparts on the drafting table. Before you can perform simple tasks in 3D you will need to know how to move around in 3D space. The UCS, PLAN, and VPOINT commands are some of the first you will need to become familiar with.

UCS
The User Coordinate System will be used to move the Origin of 0,0 to a new point in 3D space. The X, Y, and Z options will be used to rotate an axes into proper orientation. The UCS command has many more and sophisticated options, however these four will get you well underway. It may take you several attempts to place the UCS exactly where you want it, so I suggest that you use the  Save option to name your 3D orientation so you can easily retrieve it when you need it again.

PLAN
Once a new UCS is established, you may want to work in a plan view. This will simulate the 2D drafting feeling while you are working in 3D space. Although you can get to a plan view using the Vpoint command, it is easier to just type Plan at the command prompt and select the current UCS.

VPOINT
Moving about a 3D drawing can become disorienting very quickly. A good way to get re-oriented with your drawing would be to use the Vpoint command. Type Vpoint 1, -1, 1 at the command prompt to switch to an isometric view of the drawing. Here you can see the location and orientation of the current UCS to determine your place in the drawing. From here you can type the plan command to return to your plan view.

CREATING The MODEL
Start a new session of AutoCAD set the SNAP to a distance of 0.25 and turn the ORTHO on. Draw a closed polyline as sketched. Now FILLET the angle with a radius of .025 at the points where the sides meet as shown. The 2D profile is now complete, now it is time to turn the flat profile into a 3D object. At the command prompt type Extrude and select the 2D polyline, and extrude the object to a height of 1.0 and a 0.0 taper angle. Be sure that you are set to a layer that you want the object to be on when the extrude command is executed, as this command will draw all of the selected and new entities on the current layer. Lets get to a view that shows us that the object is now 3D. Type the VPOINT command and get to an isometric view by typing in 1, -1, 1 at the prompt for the view point. Next you need to assign a User Coordinate System that will let you work on a plan view of the object and will allow you to place four tapered holes. To create this UCS at the command promp type UCS and then type O, when AutoCAD prompts for the origin point, use an object snap end point to select the shown corner. In order for the UCS to move to the origin, you must have the UCSICON set to ORigin. The plus sign in the icon at the point of origin is the indicator that the icon is at the current origin and the X and Y arrows are showing your orientation in 3D space. To place the holes, the face of the part must be aligned with the UCS. To achieve this you will need to rotate the UCS twice, once about the Y axis and once about the Z axis. First the Z axis. Type UCS at the command prompt then type Z when the AutoCAD prompt request a degree, enter 90. The UCS should appear as in this graphic. For the inside face of the bracket to be our plan working environment, the UCS needs to be rotated down 90 degrees, using the same commands as described for the Z axis, but type Y in the place of the Z, then the UCS should appear as in this graphic. Now would be a good time to save the UCS. To do this, at the command prompt type UCS then S then FACE1. To show the current UCS in plan, at the command prompt, type PLAN with two enters. Since the current UCS is set to the top plain of the part, and we are viewing the part in plan, we have semi recreated a simple 2D drawing, where the plain in which we will place the four tapered holes are essentially in the same space as any 2D drawing which would be a UCS of 0, 0, 0. To add the tapered holes to our part, we will use a single 3D cone, copy that cone and subtract them from our part. To create the first hole, at the command prompt type  CONE, then 0.625, 0.625 [enter] then 0.125 [enter] then -0.5 [enter]. Your drawing should appear as in this graphic. Copy the cone to 3 other places using the COPY command with the MULTIPLE option as shown. Lets check our part by getting the view back to an isometric by using the VPOINT command. Now that all of the holes are placed, we can now ready to render the part. To combine the extruded polyline and the four cones into a single entity, you will need to use the SUBTRACT command. At the command prompt, type SUBTRACT, the select objects prompt is asking you to select the objects that you want to keep, select the polyline. Now AutoCAD is prompting you to select the objects to subtract, select the cones. Now your part is ready for  rendering.