Android

I want to build my own device (screen, keyboard, etc) and I want it to use android.

I can build the hardware no problem.

I mean I can easily make a program, compile it, and move it to the ROM.
The problem is how to install android on it.

Do I need to download the Android source and compile it for my device?

Where is it, and any info about how to do it?

Any help is appreciated!
Thanks!
CoderWalker