Well, they are out in shops.
I thought this may be fun and interesting.
Can you name a book cover that has something hidden in the art?
Graham Base springs to mind.
I got the idea from a Coke poster that went up years ago, but was promptly recalled. This was due to an image that was hidden in the ice. Let's just say they weren't selling lip stick and leave it at that. I know of at least one that fell off the truck on the way back for trashing, I would suspect there were more, it would be quite a collectable. I often inspect the side of coke fridges very closely now.
Have a novel with something of interest hidden in the art work? Please let us know!
I remember an illustrator on the podcast put a rat's head in paintings. Anyone know his name?