Raspberry Pi Stand-Alone Programmer
QCPete 
Introduction
With the power of Raspberry Pi, Python, avrdude, a custom HAT with cable adapter, we developed our own spin on AVR programming that turned out pretty darn robust. In addition to creating a stand alone solution, it was a great experiment to learn more about running a Raspberry Pi "headless", auto-launching python modules on bootup, file management, file parsing, general GPIO control, using the built-in SPI hardware on the Raspberry Pi, and even some logic level conversion.
If you'd like to create your own "headless" AVR programmer, all of the hardware design files and code are hosted on a GitHub here:
The commit history tells a lot of this story, but this tutorial fills in some of the gaps and includes more general information that is helpful outside of our specific application.