You’re welcome! I will develop a bit on the accessibility comment I made:
You could definitely make this a full game with lots of illustrations for children to play around. I would recommend that the clicking area has touch-targets large enough to see and interact with easily, you can take a look here at Xbox Accessibility Guidelines and their recommended minimum sizes (so you’d do that or more) https://learn.microsoft.com/en-us/gaming/accessibility/xbox-accessibility-guidelines/107
You could also make a simplified version where the kids can click just the hat and change color but you provide already the hat with correct ‘shadows’ and light. This, made keyboard and screen reader accessible, would make kids with low vision or blind be able to paint their own as well. The cherry on top of the cake would be having an option to save and print it.
This absolutely has a massive potential.
For kids I’d provide some more vivid color options too.
There’s a website that kinda does this and it’s very inclusive: https://sinterklaasjournaal.ntr.nl/ & https://www.youtube.com/watch?v=rRmk0joqdqg