Seesaw
This was a pretty quick and easy project. My third one from this site, as well as being my third one ever. We rented a mitre saw to cut the wood (and cut wood for a few more projects we had on the go at the same time), and then it was just a matter of staining it and putting it together. The staining and waiting for it to dry actually took a couple of weeks, mostly because we don't have a lot of room to do that, so couldn't do it all at once, and it wouldn't stop raining. Once we actually had that done, drilling and assembling only took 2-3 hours at most. (Maybe even less, but hard to judge as I had two children helping the whole time.)
I've put a video of it in use on my blog as well. :)