Magical tape measure

"He pulled a long tape measure with silver markings out of his pocket...He measured Harry from shoulder to finger, then wrist to elbow, shoulder to floor, knee to armpit and round his head...Harry suddenly realized that the tape measure, which was measuring between his nostrils, was doing this on its own. Mr. Ollivander was flitting around the shelves, taking down boxes. "That will do," he said, and the tape measure crumpled into a heap on the floor."

- The tape measure measures Harry Potter

Mr. Ollivander once owned a tape measure that he used to measure wizards and witches when preparing them a wand. This tape measure moved on its own accord. That way Ollivander could sort through he many shelves while it measured.