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 video tutorial will show you how to make the x-axis motor mount for a CNC router. The x-axis motor mount is the easiest because, first, you've done two already and you're an expert, and last because there are few obstructions in your way. In this build, just like the last z-axis mount, the process is exactly the same. There is one minor change, but it will be preferred by most builders. Each motor mounting hole will contain a screw and three nuts. One nut lodged into the hole in the mount. Two nuts between the mount and the motor. These nuts will add extra support by tightening one to the motor side and one to the MDF side. This way, the motor is stabalized and the nut against the MDF is tensioning wth the nut in the hole so the nut in the hole will not have the tendency to move.