clear glass/paper adhesive?

[laurenrambles.livejournal.com]

my brother just moved into a room with a door that has glass panes. to cover them, i told him to cut up a poster and attatch them facing out, so you see the pieces from the outside. we plan to glue them on the inside though, somehow. but im not sure what kind of glue/tape/adhesive to use. it needs to stick the paper to glass, but still be really clear so it wont show from the outside. anyone know a good way to do this?