Paint Star Piece
From the Super Mario Wiki
The Paint Star Pieces are items in Paper Mario: Color Splash. They are the pieces of the blue Mini Paint Star in the Sacred Forest, and there are five in total. The Mini Paint Star was taken apart by several Small Goomba Gangs, who took the pieces throughout the level. Once Mario collects all five pieces, he can repair the Mini Paint Star.
Locations of the Paint Star Pieces