Q:

Where is the AWS Tools for Windows PowerShell Source Code

I would like to extend the AWS PowerShell commands.  Many of the AWS SDKs are on GitHub, for example AWS .NET SDK, but not the AWS Tools for Windows PowerShell. 

A:

I am not sure if you have found this already, but it is open source now 
https://github.com/aws/aws-tools-for-powershell

