A toy, and a fun one to watch: nothing is exported or printed. Choose one of three virtual printers (a bed-slinger, an enclosed CoreXY, or a delta), then load an STL, OBJ, 3MF or PLY model, one of the nine built-in samples, or a product photo, and the printer builds it up layer by layer. Each machine has its own geometry and a working control panel.
Everything happens in the browser. Models are sliced client-side, there is no backend, and files never leave your device. The page makes no third-party requests and ships with a strict Content-Security-Policy. Photo-to-3D is marked beta, since outlining an object from a single photo is rough.
Try the live demo, or read the source on GitHub (MIT licensed).