Its supposed to be an arrowhead, I still have some more refining of the design to do so it looks more realistic, at the moment I just cut it out of some tape and stick it to the knife as my template. But I use a power supply, which is a device that converts ac power to dc power if you are unfamiliar (a car battery charger can work too) and salt water as the electrolyte solution for etching. I hook the positive wire to the knife and the negative to a q-tip saturated with salt water, and it eats away the metal. It takes 30 seconds to a minute and its fully etched.I love the simplicity of it. Nothing fancy, but dang man, that's a looker for sure.
Out curiosity , how are you making the tree logo?