In the left playground when facing the train you will find the Train (2) statue on top of the yellow slide. After you’ve grabbed that walk forward through the Game Station and get up on the train platform. On this platform you will find three levers. The only one we can pull right now is the far left. Pull this lever and wait a little bit. The opening to Musical Memory will slowly roll open, allowing you to access this area.
Go down into Musical Memory. Follow the linear path forward until you find a hole in the ground. Drop down through this hole and continue forward until you reach a dark room with four buttons in it. This room is called the Molding Room and it is where we will get the Green Hand.