So, a while ago, I randomly ran across Wintergatan's Marble Machine on YouTube. Well, it's a fun vid, and epic nerdiness. Turns out, once you watch one "amazing marble" machine vid, YouTube suggests (no surprise) many more. It's really wild the creativity and engineering that goes into these things, which means the hundreds of hours of time. It's engineering and art, all bundled together. As far as I'm concerned, any instrument using marbles is madness ... Some people use of the shelf kits to create crazy "tumbling domino" like runs... ...and some people just do completely custom work... ... and in any case, it's all crazy impressive.
Thing I like, and you might also like.