I haven't had much free time to explore this idea, but tonight I was able to successfully etch aluminum using supplies that I had on hand.
Here's an example of a labeled switch plate I turned out for my jet sled project. I used a vinyl stencil cut on a Silhouette Portrait as the resist, and electro-etched it with a car battery and a salt water solution.
In a nutshell, one masks off everything that should NOT be etched on the aluminum and attaches a length of wire to the back of the aluminum object with electrical tape; this wire is connected to the positive terminal on a car battery. Then, one attaches another piece of wire to a piece of scrap aluminum; this wire is attached to the negative terminal of the battery. Then, in a glass or plastic dish, both the anode (the piece you want to etch) and the cathode (the scrap aluminum) are placed as far apart as possible and a solution of water with as much salt as can be dissolved is added. The cathode (scrap aluminum) will bubble like mad, and the exposed areas of your good piece will be etched.
It appears that the higher the amperage, the faster the etch. As you can see in the following photos, the "G" in the word "BILGE" is over etched, as my vinyl resist lifted. I had similar problems when I used laser printer toner that was transferred on to aluminum, too; the laser toner was printed to a sheet of glossy magazine paper, then ironed on to the aluminum (one has to print a reverse image of the "artwork" when using this technique) and the paper is removed with running water and gentle rubs with a fingers.
If the amps were scaled back, it appears both the laser printer and vinyl resists would work better. I'm thinking of using an old wall-wart left over from a long-lost cell phone as my next power supply.
Cheers,
Scott
