To scrutinize objects at the nanoscale, scientists use an atomic force microscope (AFM). But the instruments can cost $100,000 a pop. Last year, an international group of students built a roughly $250 prototype from LEGOs, hacked electronics, and 3-D–printed parts. Like a regular AFM, the LEGO one constructs images by measuring the distance between a sample and a probe on its arm. This summer, students worked to refine the model and bring its price below $100.