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.
Maybe in the office, art studio or the used book/game/comic store This a cool idea for art work in a space. If it is a temporary space for you, cover walls with white butcher paper, then go to town drawing.