Hands-on explainers, in the spirit of Bartosz Ciechanowski. None of these are videos. Every figure is a live model you can drag, spin, and poke at. Some of them make noise.
How the most common lock in the world works, and how it's picked. Spin a real 3D cutaway, slide the key in, and pick it open pin by pin while it clicks.
How headphones erase sound with more sound. The figures actually play audio, so you can hear two waves cancel into silence.
What happens to light as it falls in. Real Schwarzschild geodesics, the photon sphere, the event horizon, and gravitational lensing you can orbit around.