ESP3D is an Arduino/PlatformIO firmware for ESP8266/ESP32 microcontrollers that turns them into a full-featured 3D printer, CNC, or sand-table controller. It provides a Web UI via an embedded HTTP server, WebDAV for file management, WebSocket/Telnet/FTP/Bluetooth for remote control, Lua scripting for automation, sensor support (DHT, BMx280), display drivers (LVGL, TFT_eSPI, OLED), and SD/flash filesystems. The firmware is highly configurable through compile-time feature flags and supports both ESP32 and ESP8266 platforms. The codebase is modular with service lifecycle management, a command dispatch system, and hardware abstraction layers. While functional and well-structured for an embedded project, it suffers from heavy use of preprocessor conditionals, some code duplication across platforms, and a large number of vendored third-party libraries that increase maintenance surface.