What does on spec mean?

It's short for on speculation. Work that is done in anticipation of a benefit that may not be realized. More narrowly this applies to work without a contract or order because you hope a client will select your work and pay you for it. This seemed apropos in the sense that I'm doing something that no one has requested. The benefit I'm hoping for is enjoying the experience. And if not, I'll definitely stop. I have a feeling that's everyone's unstated plan; I was just fishing for a name and this is what came to mind.