If you want something mechanical I'd suggest trying to make an ornithopter, which is about as mechanically-inclined as it gets. I'm admittedly interested and working on designs of these myself, and I think there's a lot of opportunity here to try something new and innovative.. if you're really up for it, that is.
One thing that's really interesting is how the common house fly has less brain processing than an electric toaster has to process when toast is done, yet it flies every bit as well as any full computer processor on-board jet aircraft..
So, the idea here is that with the right sensors making almost direct influence on how the wings move you can have precise and stable flight, without all that computer hardware weighing down the ornithopter.
Well, there's many other ideas to try with ornithopters, and even getting one to fly at all is probably enough of a project in of itself. You might want to just avoid it all if you're not all that confident..