This is an instructable about etching brass with electricity to make a badge. It is a well-known process and very easy to achieve.
It is based on the process explained in http://www.greenart.info/galvetch/contfram.htm and http://steampunkworkshop.com/electroetch.shtml.
Lots of information and very well detailed. I also want to enter in a contest of a famous webpage among hackers (wink, wink) and plan to have a workshop based on this.

Step 1: Warning

Just a few friendly reminders :
The chemicals used, altough not dangerous , can be toxic to certain level.
Be respectful with electricity. She makes no friends.
Metal edges can be point and sharp, do not mess with them.

Step 2: Materials

- Power supply (Car batery, psu from a computer, batery charger, ¿solar panel anyone?)
- Metalic salt (copper sulfate works, but also a mixture of vinegar, water and table salt)
- Metal bar or mesh (as counter electrode)
- Magazine paper (glossy paper)
- Plastic container
- Iron
- Brass plate
- Laser printer (and only a laser printer, not inkjet nor gutenberg´s printer)
- electric wire and tape
- Tin
- A paper clip
- Pliers

Step 3: Select and Edit Image

As a very well versed person of the XXI century I have several editing softwares to make and modify a picture. You might decide yourself among free software like the gimp (http://www.gimp.org) or inkscape (http://inkscape.org/) which are very good software but I chose... MSPaint, quick and dirty , yaaaaiiiii.
Your image will have to be in blck and white (old style, old technique, oh well) and reversed, because when you iron it on the brass it will flip, like when you read the image of a book in a mirror.

Step 4: Transfer Image

Now clean your brass plate reaaaaally well. Scrub it with a scouring pad. The key here is to leave small grooves in the metal so the toner will attach better to it when you heat it. Once you are satisfied with your results... turn again to clean it. Be sure to leave no fat or dirt on it. Turn the iron to its maximum setting. Stick your paper with the picture you printed facing the now clean brass with some tape. And... iron it. Press and iron, take your time to learn the process. Make sure that you tranfer all the toner to the letal. Usually 3 minutes is more than enough of pressing and heating. Be careful because the metal will get hot. Throw it into the water and peel with your fingers the paper. Fingers is the best, tootbrush might work but you risk to remove some poorly attached toner.

Step 5: Galva-Etch

Excellent, now we are half way to the end!. Fill in your plastic container with water and the salt to turn it into an electrolyte (this is, a conducting liquid). Inmerse your working piece (brass) in the bath and connect it to the positive pole of your PSU. Connect the negative pole to your sacrifice electrode (SS mesh in my case). Turn it On!!! A voltage of 12 volts is a good start, no bubbles should be seen. Leave for 30 minutes and check it from time to time to see that the toner is not faling apart (sometimes it happens) . When you are done switch it off and wash your piece.