Had when i worked in a preschool and kids love them! I would use colored sand instead of white salt. DIY salt tray with alphabet cards. Easy to make and kids have fun smoothing out the salt after correctly making the letter
How To : Adobe Illustrator Geometric Art. This is a very interesting type of art. I do like how it uses simple shapes to create a portrait. I know for a fact that you can do this easily in Photoshop with one of the brush tools.