The spray paint works very well. Just a dot will last for 3-4 months. I have a few Rhode Island Reds and you cannot tell them apart to save your life. My daughter now knows which is her favorite (Jewel is what she nemed it), it has a green spot on the tail.
That's an idea I haven't thought of. Would they get pecked at (the bands or feet)? Would any certain color be better?
I feel a little bad if I use rubber bands.
I have used a little spray paint on a couple so I could tell them apart. No ill effects that I could see. Just a little green...