"I am the instrument between an artist's hand and the canvas. I can be as fine as a hair or as wide as a hand. I hold colour but I have none of my own. What am I?"

Answer: A Paintbrush. A paintbrush transfers paint from palette to canvas. Its bristles range from ultra-fine for detail work to very wide for broad strokes. The brush itself has no inherent colour — it merely carries whatever the artist puts on it.