Lay out the objects you plan to use in your shadow box to determine how many items you need to fill the space.
Glue a foam square to the back of each photograph you are going to use, no larger than 1/3 of the size of the picture. Use the glue gun for this. Try to center the square to keep it from being visible. Allow the glue to dry for one to two minutes.
Place the photos in the shadow box according to your layout plan. The foam squares will give your photos elevation and a shadow of their own in the display. While using foam is optional, it's a great way to make photos more eye-catching.
Place other trinkets and small souvenirs around the photos in the shadow box according to your layout plan. Souvenir spoons, seashells and even tickets to events make great conversation starters.