Bob Bumgarner, a Physics teacher at King George High School, programmed a Micro:bit so that it could be used as a photogate, a device for very accurate timing. He also designed a holder for the bit using Tinkercad, and 3D printed it. Bob was generous enough to provide his description of the project, the Micro:bit code, and the .stl file for the holder. This is a very practical use for both the micro:bit and 3D design/printing. As Bob points out, it is a way to save a good bit of money on lab equipment. To read Bob's report click here, the code is here, and the .stl file is here.
Photogate code for Micro:bit
Photogate holder in Tinkercad