A CNC router machine is probably the most useful tool a hobbyist can own, but the price for a CNC machine on the market is way more than the average hobbyist is willing to spend. You can build your own CNC with very basic tools, little knowledge of machinery, mechanics, or electronics, but be warned, these machines are inherently dangerous, so wear the proper protection and use common sense. At the very least, read the instructions and precautions on every tool you use.
Now, a CNC stands for Computer Numerical Control, but that is gibberish. It does hint you to the fact that something is controlled, and probably by a computer. It's really a mechanism that interfaces to a computer to control its movements, similar to a robot, but this machine has a specific function. It cuts or shapes things with this control. In essence, a computer precisely controls a cutting tool, like a router for instance, to cut materials such as wood, plastic or metals into shapes only bounded by your imagination.
This three-part video tutorial will show you how to draw a part in CAD and cut it out with the CNC router.
This is the entire process from drawing a part in CAD (Computer Assisted/Aided Design) to the final product that is cut out from the CNC machine. This series will step you through the design of a very simple object that uses drills and profiles. Drills are simply holes created from the end mill (router bit) into the material and profiles are horizontal cuts, usually in geometric form, that create various shapes.
Once you create the design, use the machining functions. Limit the machining functions to drilling and profiling. Three holes will be made using the spiraling drill technique, where the bit is smaller than the hole. I will also show how to make similar holes with profiling; however, you will see that the drilling method is cleaner and makes a perfect circle. In addition, the profiling will be used to cut out the final object.