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 tutorials will show you how to build the stands for the gantry table for a CNC router. The CNC router has a table, right? The flat piece that you put the stuff on to cut, right? Well, that piece has this thing called the gantry riding over it. How does that gantry move? It needs to hug this surface and requires a piece underneath. In other words, the gantry cannot move unless this surface is lifted above the ground to accomodate the gantry support and the motor underneath. Here, you will build the x-axis front and back stands.