There are several instructables for "etching with salt water and electricity", check them. My addition here is to share a technique to create the mask of the image to etch using paper and a laser or inkjet printer.
Full disclosure: I learned this technique reading this great page:
, PLEASE check it.
The key is to use the paper from magazines or inserts in newspapers, the ones with the shinny surface:
- print you image (horizontally flipped and as a negative) on this paper
- use an iron at top heat and a popsicle stick to make sure the ink from the printed image sticks into the can's surface
- soak the tin in warm water to soften the paper before taking it away.
- do the etching
- Optional: use paint thinner or nail polish thinner to remove the ink from the can. Keep the black ink if you think it adds art value to your creation.