Selling coloring books on Amazon KDP is a low-cost, scalable way to create a stream of passive income. By focusing on niche markets, creating high-quality designs, and implementing effective marketing strategies, you can reach a broad audience interested in the creativity and relaxation that coloring books offer. With a variety of niches to explore and the flexibility of print-on-demand, publishing coloring books on KDP can be a profitable venture for artists, authors, and entrepreneurs alike.