Bucket of Plaster
From the Super Mario Wiki
The Bucket of Plaster is an item in the SNES release of Mario's Time Machine. It is given by one of Verrocchio's apprentices to Mario after he goes back in time to Florence in order to return Leonardo da Vinci's Notebook. The apprentice, being too busy with other work, gives the Bucket to Mario and asks him to deliver it to Michelangelo Buonarroti. Michelangelo needs the plaster to test a newly developed form of art. Michelangelo refuses to give Mario additional information about the area and history until he is given the Bucket of Plaster. Once he has it, he elaborates that he has been commissioned by Pope Julius II to completely paint the Sistine Chapel's ceiling with frescoes. He then puts it away for safekeeping and continues talking to Mario.