Epic Mickey 2: The Power of Two

After coming back to your home just after you obtain the brush in the magical plain, use thinner on the back wall with the TV to get back into Yen Sid's lab. From here, use thinner on the holding block behind the big object in the main room for it to crash down so you can ascend the room. Once at the top you enter a large room with a picture in the middle, you can use either paint or thinner to fill it in (use Paint to get a Unique Pin). Once done, jump through it to proceed and the trophy will pop.