DIY Sand and Rock Box by FSPDT. Gdjk -> made this with toilet rolls (aka tunnels) and moon sand instead of play sand. My son loved playing with it. The moon sand cleans up nicely indoors but play sand will be easier to play with when using the small cars.
This is the Montessori method to feeding babies and toddlers. The foundation is to teach basic life skills and create an environment where they will have success. This method is at my kids' school and seriously works.