You can't. Check the announcement of the game "Fat Goose Gym". The golden treasure chest of Fat Goose Gym can't be synthesized. This is the rule of the game. Fat Goose Gym is a mobile phone game. The background is set in the "Fat Goose Gym", and the player will play the role of the manager of the gym, get materials through the synthetic gameplay, and unlock new areas, new decorations and new fat geese in the gym.