I've built one of these, and it was a lot of fun.

The interesting thing was, to me, how this automation script blossomed over time into what now stands as a utility very much like ant and nant. To give you an idea of how far I went, here is the list of "modules" that I could batch together and configure for the many different flavours of "build" I had on my plate at the time:

I controlled builds by composing INI files (guess which platform I was on ;-), and I had a simple GUI I used to check/uncheck different steps in each. I was about to launch into writing a miniature scripting language, or perhaps just a mechanism for passing state information between steps, when I realised that I was reinventing the wheel in a major way and it was time to stop. Soon after, I changed jobs and the need for such a tool diminished.