So many coloring books are licensed IPs, none of which Robin is familiar with, and none of which I’m enthusiastic about introducing him to.
If I were to design something for Robin, it would feature lots of stars and flowers. So now I’m imagining a sort of magical setting in the night sky, with characters who take care of stars and have gardens and horses and dogs and cats and giant trucks. Sort of Rainbow Brite/Pixie Hollow/Monster Truck.
I suppose Care Bears comes close, except for too plushie, no horses or giant trucks, and apparently nearly dead as a franchise except for at Hot Topic.