I love this idea. I would do it, get removable wall paper. - "A neighbour of mine has one wall in their house papered like this. Every time a new guest comes in, they are asked to colour-in a character and initial it.
and have posted this company and their wallpaper many times.what a great collection and can you imagine the story telling that could go on for years with such wonderful animals! little hands: Little Hands Wallpaper Mural - Falling II