Etching
Etching is a process in which strong acids are used to cut into parts of a metal surface to create a design.
Related Article: engraving
Printed Circuit Board (PCB) Etching
A PCB is used to physically support and electrically connect a circuit's components. The boards themselves are made of a non-conductive substrate laminated with copper foil. After a circuit is designed, the parts of the board that will serve as solder points or connections between components (called traces) are covered in an etch-resistant ink.
Related Software: gEDA TinyCAD Kicad
Toner Transfer
Print your circuit layout onto a piece of glossy magazine paper using a laser printer set to its darkest print setting. An inkjet printer will not work using this technique. If you do not have access to a laser printer you could print your design on white paper and use a photocopier to create your transfer pattern. Using the pages of a magazine works well because the toner will not fix itself glossy paper very well and can be easily transferred to the copper board.
At this point you will need to prepare the board for the transfer. Be careful not to touch the copper surface as the oils from your skin will interfere with the transfer process. First use a scrubbing pad (any type except for steel wool) to lightly buff copper and then dry with a moist cloth.
Set your iron to the hottest setting, place the magazine paper print side down onto your board, and press the iron firmly onto the magazine paper. Keep pressing firmly for around one minute and try not to move the iron as this will smudge your design. After the first minute you can begin slowly moving the iron while ensuring that the paper stays in place. You'll want to keep applying pressure at this point.
Allow the board to cool, and then place it in cold water for a five minute soak. Then peel the paper from the board until only the toner remains.
Chemical Etching
The etching process removes the unwanted portions of copper while leaving the board itself intact.
Keep in mind that these chemicals need to be handled with respect -- gloves and safety goggles are highly recommended!
One option is using a solution of 1-part muriatic acidW to 2-parts hydrogen peroxideW and another choice is using ferric chlorideW. Often boards are placed into baths of acid, which is quite a waste. A less resource intensive approach is placing a tablespoon of ferric chloride solution onto 2 inch square sponge and then scrubbing your board directly with the sponge.
Instructables guide to the sponge and ferric chloride method.
Drilling
The last step before placing and soldering your parts if drilling holes through a PCB. Typically tiny drill bits made of solid tungsten carbide are used along with a drill press.