Put painter's tape on the wall, then put double sided tape on top of the painter's tape. Stick posters, etc. on the double sided tape. In the end you can remove the poster and painter's tape without damaging the wall.
hanging "frame" for poster or fabric print, etc... made with 2 1x2' boards each top and bottom, hole drilled at each end with screw/bolt thru, plus washer on front if want, add bit of cardboard or sticky tape, etc, between boards as buffering...long piece of twine with open loop tied at each end slipped over bolt between boards...tighten and hang