This document provides instructions for building an inexpensive Arduino-compatible board from scratch. It outlines the requirements, bill of materials, schematics, assembly instructions, and testing procedures. The board can be built for under $5 and replaces the Arduino board for final embedded projects. Components are soldered onto a stripboard and include an ATmega328P microcontroller, 16MHz crystal oscillator, voltage regulator, programming header, and an LED for testing. The assembled board is 4.5cm x 5.5cm in size and can run Arduino sketches over a USB connection.