Why Mechanical keyboards
The main difference between mechanical and a prebuilt keyboard that comes with your computer is probably the switches. These switches are made of several moving parts when you press the key, the two metal contacts connect, registering your keypress to the keyboard’s circuitry.
the circuitry is called a PCB (printed circuit board) PCBs are used in all but the simplest electronic products. But in this case its the brain of the keyboard.
Other than that, you need a plate (or not depend on your preference of the sound and feel of the keys) between your CPB and the switches to give it extra crisp.
And keycaps to protect the switches and your fingers. All of the above can be put into a case of your choice.
My favorite part of building a mechanical keyboard is that you can put your own design in them. you can choose from the design of each part to the feel and sound your keyboards make. Also building it by yourself is a lot of fun!