Oops, I did it again...

After my first big exam last Friday, I decided that I needed a couple of days without reading and studying. The next exam is in 5 weeks and the third two weeks later. Not too far away, but it allowed me to catch breath and do something else for a while. So I did another puzzle. I bought it 4 months ago and wanted to do it much earlier, but I never found the time. I finished it in under 72 hours, 10 of them were spent actually working on it.