Here's the bird I put together from the Sydney Opera House set (21012).
For the base I tried to add what levels I could. I also wanted to do some water with those clear bricks.
Unfortunately, the bird is rather fragile. It can be moved around with its base well enough, but it fell apart a lot while trying to put it all together. The limited number of pieces made for some less than ideal build choices.
Overall it was an interesting challenge. Full build instructions and the MLCad file can be found HERE.