I've actually been meaning to post this since Christmas. Big Ginger Dave went to a lot of effort using Lego Factory to create a Lego walrus for me (link – the first one is Dave's). It was fun to put together, although I had to download the Lego Factory software and the model and use that to figure out how to do it! Even with that, it took about two hours to assemble one of them; I haven't got around to the second yet ;-). Just one note of annoyance: the Lego software seems awfully buggy and has one of the worst UIs that I've ever seen. Avoid it until at least the next major version.
