This is a long video, but it's strangely captivating. You'll watch the whole thing without even realizing it.

 

I don't even know what to say. It took SIX HUNDRED HOURS to construct, runs about 101 feet, uses 500 balls...and just blows my mind.

Although I will say, it could be made infinitely better if it used this music underneath (press play on both vids, it'll be great):