A whole book. With a beginning, a middle, an end and everything!
Just to put this momentous occasion into context: I have wanted to write a book since I was about eight years old. That was - not to put too fine a point on it - a really long time ago. The ensuing 20-odd years have consisted of starting about a million books but never finishing any of them.
I don't suffer with writer's block so much as 'writer's over-active imagination'. Inevitably, halfway through one book, I would get an amazing idea for another and just have to start it right away. And then this pattern pretty much repeated itself over and over and over for years...