Visual elements for your science fair project are the second most important element of your project. It is your display board. This is because these are what the judges are going to use to score your project. This means you need to spend a lot of time developing quality visual elements.
The type of visual elements your science fair project needs will depend greatly on what your science fair project is about. However, all science fair projects need are display boards. If you are planning on enter a big fair like ISEF or Google, you will need a Monster Board.
Your display board will include information about each step in the scientific method that you took, it will include your data and your data analysis. Your visual display board will also need to include graphs, drawings and photographs that illustrate the set up of your experiment, the equipment that you used and the results that you got.
In addition to your display board, you may also need other types of visual elements. For example, if you are working on a medical science fair project then you may need a 3D model of the body part or system that your project is based on. On the other hand, if you are working on a robotics science project, then you will want to have the robots that you built on site so you can demonstrate what they can do.
If you need ideas for visual elements for your science fair projects then you can conduct outside research. One blog that I found helpful is Science Blogs. Use this site for generating ideas for visual elements and projects.