Use PowerPoint to create giant letters in any font. Use pictures, textures, or color to fill to fit any theme. You can also print out on bright paper (and laminate) for cheap and durable bulletin board letters. Great way to have just the letters you need.
What a great positive group activity! Have one person sit on a chair in front of a white board while the others wrote a positive phrase about them. Take a picture to give to each person. A very creative and positive group activity.