Working 3D printers existed long time, but only SLS and very expensive. Only in 2000s appear things important for cheap 3D printer: 1. Cheap power semiconduct

Working 3D printers existed long time, but only SLS and very expensive. Only in 2000s appear things important for cheap 3D printer: 1. Cheap power semiconductors. 2. Cheap 32-bit microcontrollers. 3. Powerful computers, to run slicer, and free slicer. 4. For photo-sensitive resin appear large 2nd market of powerful semiconductor lasers and light-modulators (from DLP projectors). To be more exact, FIRST powerful transistors appear in 1970s, but become cheap in 1990s; microcontrollers similar, but before 2000s cheap 32-bit does not existed; microcomputers become enough powerful for 3D printing in late 1990s and appeared home CNC motion; lasers are still grow, they now have something like Moore law. So to conclude, yes, sum of technologies need for cheap 3D printer appeared around Y2K, but then few years spend by fans to construct practice equipment and make first shipment to customer (Prusa made his design around 2009).