Supported OS & Compiler
Windows:
OS: Windows 8.1 and Windows 10
Compilers: Visual Studio 2015 (AVID approved) or Visual Studio 2017 (Not fully AVID tested but works)
MacOS:
OS: 10.11 and higher
Compilers: Xcode 7 and higher

AAX Parameter Count
The AAX monolithic parameters paradigm requires a queue of parameters for tight sync with the GUI and audio. This is part of a static defintion and can't be changed programmatically after the object has been created. The definition of the maximum number of parameters is in the AAXPluginParameters.h file and is set to a value of 64. If your plugin needs more than 64 parameters, you need to change this value (OK if this is a large number, but it needs to be changed before compiling). See:

#define kSynchronizedParameterQueueSize 64

in the AAXPluginParameters.h file if you need to change it!

AAX Library
You must compile the AAX Base Library first. You only need to do this once per SDK release (or if you update your compiler to a newer version). You can find the XCode and Visual Studio generated library projects in these folders:

AAX_SDK/Libs/AAXLibrary/WinBuild

or

AAX_SDK/Libs/AAXLibrary/MacBuild

Open the project file and compile your project using the same compiler that you will use to compile your project. Anytime you change compilers, you must re-compile the library with your new compiler. The result of the library compilation will be:

MacOS
Starting with SDK 2.3.1, there are two separate MacOS/Xcode library targets depending on the use the std:: library. ASPiK (and all of the AAX demo plugins) require the "_libcpp" versions of the libraries so choose the correct target when building these libs.
AAX_SDK/Libs/Debug/libAAXLibrary_libcpp.a
AAX_SDK/Libs/Release/libAAXLibrary_libcpp.a

Windows x64
AAX_SDK/Libs/Debug/AAXLibrary_x64_D.lib
AAX_SDK/Libs/Release/AAXLibrary_x64.lib

Open the compiler project for your newly generated project. With these libraries built, you can now re-build the solution to complete the ASPiK project.

Finding your Plugin
Your finished plugin will be located in the following sub-folder:

AAX_SDK/myprojects/(project name)/mac_build/AAX/(config)

or

AAX_SDK/myprojects/(project name)/win_build/AAX/(config)

where (config) is either Debug or Release, depending on how you built the project.

Copy the .aaxplugin into your AAX plugin folder. You must to this manually because in both operating systems, the target folder is admin-protected which prohibits the copy mechanism from being done programmatically during compilation.

MacOS
/Library/Application Support/Avid/Audio/Plug-Ins

Windows
C:\Program Files\Common Files\Avid\Audio\Plug-Ins

Now you can run your Pro Tools Developer's Build to test your plugin and generate the Presets for it.