The most challenging part of the process was the original animal skull references. “The mouse skull and bird skull were especially difficult. They have all those little holes, crevices, and fine details and it’s very difficult to imagine their shape in 3D.” But the Czech illustrator didn’t give up and collected all the relevant material from universities and museum sites.

Filip tried his best to make the cartoon skulls look like they were based on their real-life counterparts. However, “I had no choice but to guess a lot of it and make some quite creative decisions.” He gave an example: “Obviously, a mouse skull wouldn’t have ears or that arching pointy part defining the eye shape, but without the ears and clearly defined eye shape it just didn’t look like the cartoon at all!” Apparently, without this creative addition, “it looked very odd and creepy!”