A collage that captures moments throughout the year or over the course of the student's study can be a marvelous way to honor new graduates. Choose photos from school events and ask for submissions from school clubs and organizations. Also ask for photos from students that show the friendships and special moments that were a part of their time at school together. You can create a collage in a program like Photoshop or a freeware program such as GIMP.
The theme of your sign designs will be paramount in choosing font styles and graphics for your graduation sign. For example, a serious or classical design will incorporate a formal font like Times New Roman when adding text to the imagery to gives the sign a more official aesthetic. A funny design would use a font style that adds a whimsical feel to your sign. Kristen ITC would be a good selection if, for instance, you were creating a design or text with a theme that expresses to graduates how far they've come. Your text line could be "You've come a long way, baby," with a photo college below the text that shows double framed images that show some of the graduating class as babies on one side and adults on the other.
If your goal is to create a low-tech sign simply to add your congratulations to a chorus of other signs, a handmade sign can be the perfect choice. Purchase the supplies you will need such as poster board, markers, stencils and even glitter. For a personalized touch, have various people sign the sign such as members of a sorority or staff members at your school. If you are placing the sign where it can be affected by adverse weather, add a protective coating.