When we got pregnant with our 2nd child we moved our son into a new room. We wanted to do a fun accent wall and have a playful but not to "kid" room! We collected pieces from the room from various places - most often just stumbling upon something that we knew we wanted to incorporate in the room.
My favorite part of the room is the wallpaper! We bought removable wallpaper so we can easily take it off the wall when we switch up our son's room again. I highly recommend going this route to add an accent wall to rooms!
If you want to see more, be sure to check out this post!