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
Bubble Wrapped Blocks are also a great learning tool for literacy and numeracy activities. Children can print and trace over faint pencil lines of alphabet letters, numbers, shapes, sight words and also learning their name.
Lego learning games - exploring Lego and play dough. This is a great activity for sensory play, imaginative play, letter recognition and sight words. This would be great to use in an autism classroom while learning long vowel sounds with silent e