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 Make a Cardboard Box Marble Labyrinth Game - Frugal Fun For Boys Engineering STEM activity for kids - Build a cardboard box marble labyrinth! Get the marble through the course without it dropping into the holes.