The first question you may ask is, Why would I want to build my own Arduino UNO? Economically speaking it does not add up in your favor after you acquire the parts and consider the time it takes to put it all together. This is especially true when you consider that a Nano “clone” could be purchased for around $3! You might have a permanent use application that makes building one your best option? Maybe you just like to learn and do stuff just because you can!
The unit below is built on a prototype shield that has become the main board. For my keyer application I have no need of USB communications and I can keep the wiring down to only what is needed. The 5v regulator will soon have a small heatsink as it gets warmer than I would like.
Below is the other side of this board. I used #4-40 screws as “legs”.
Instructions for building one yourself on a solderless breadboard can be found at https://www.arduino.cc/en/Main/Standalone
Instructions on burning the bootloader with another arduino can be found at
If you run into trouble like I did by getting the “wrong” ATmega328 microcontroller you can get work around instructions at http://www.crash-bang.com/resource/bootload-atmega328/