A mechanical keyboard is the assembly the last two pages feed into. The switches (from the Dongguan and Huizhou makers) drop into a PCB, soldered or, increasingly, on hot-swap sockets, driven by a cheap ARM microcontroller and, for wireless, a Nordic or Telink radio and a battery. Over that sit a plate (aluminium, polycarbonate, FR4 or POM), stabilisers, the keycaps (double-shot ABS or dye-sub PBT), foam, and a case. The reference design is the layout, the mounting style and the PCB.
Nobody competes on the key layout, which is fixed. They compete on feel and sound, and that comes from the mounting: tray, top, gasket or spring mount, each changing how the board flexes and sounds. And on firmware: the enthusiast standard is open-source QMK/VIA (remap any key, no vendor app), while gaming and office boards usually ship a proprietary driver. Hot-swap (3- or 5-pin) versus soldered decides whether a buyer can ever change the switches.
The market is a brand layer sitting on Pearl River Delta factories. Chinese names now lead it: Akko, Royal Kludge, Keychron, Epomaker, MonsGeek, often designing in-house and owning the factory rather than just rebadging. The two live frontiers are magnetic Hall-effect boards for rapid-trigger gaming (adjustable actuation, SOCD, per-key analog) and premium materials, full-aluminium CNC cases, flex-cut PCBs, PVD weights. The same board often ships as a barebones DIY kit and a finished unit.
Compliance is light, CE, FCC and RoHS, with the real verdict coming from the enthusiast community on sound and build. The parts a brand still buys in are the keycaps (PBT dye-sub and double-shot houses), the PCB, and very often the switches themselves. Above this layer sit the names that mostly design elsewhere, Cherry, Logitech, Razer and the boutique Western customs. The houses below make for everyone else.