Flex 2 is a Free SDK

It will allow you to build the *.mxml and *.as files in the PaperToolkit/flash directory.

1. Unzip the flex_sdk_2.zip that you get from Adobe's site.
2. Put it somewhere (e.g., C:\Program Files\Adobe\Flex SDK 2)
3. You'll need to put this path's \bin into your PATH environment variable (e.g., C:\Program Files\Adobe\Flex SDK 2\bin). That directory contains mxmlc.exe, the Flex compiler.
4. To learn about Flex, go into the samples directory and run the build.bat scripts... Then, load the SWF files into a Flash player (version 9 or above).

Two good examples include the Flex explorer and the Photo Viewer.

For Full-screen support with ActionScript 3 and Flash 9, you will need to update the playerglobal.swc in your Flex SDK 2\frameworks\libs\ directory. See this link or download the file directly from here.

How to compile the PaperToolkit Flash/Flex/Apollo components:

1. TODO