Instructions
Move through the hallway where you are instructed on paint and thinner.
Enter the courtyard.
Paint or thinner the "Blotling" that resides in the courtyard.
Move Mickey to face the exit door.
Turn to the left.
Head toward the red wooden, Toon door that is near the catapult. It will be on the wall near the ramp.
Use thinner on the door to reveal a hidden chest.
Open the chest and pick up the Dark Beauty Castle pin.