The average 'QWERTY' keyboard has 101 keys in its layout on a frame of water-cut plastic.  Beneath this is the key matrix circuit board where pressed keys complete a circuit, sending a current to the memory contained in the keyboards microprocessor.  So, when 'Q' is pressed, it knows to send the same letter to the computer.  All computers can be configured to accept any different setup of keys on a keyboard.   

Hooleon offers simple do-it-yourself key overlay stickers, or more advanced do-it-yourself keys & key tops for special uses ranging from classroom needs to manufacturing purposes.

For advanced needs, we offer a multitude of color options and symbols for the keys.  To do this, plastic injection molding machines create keys that are formed under heat and pressure and expelled into container for inspection.  Blank keys after molding, are ready for imprinting with letters, symbols, pictures, etc., whatever you need the key to represent to the user.

We provide keys or you may supply your own and we imprint them for you.  

You can find more info on Custom Keyboards here.