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
The children in art class experience what it's like to draw with their feet and mouths (and elbows! This is not only a fun, action art experience, but it gives them a new appreciation and gratefulness for their hands.