Also not vertical, not gravity driven, not non-mechanically driven…and not pertaining to the topic at all, as far as I can see.
Grumpy are we?
I posted it because I think it is. While it’s a car, hence horizontal and not vertical, it shows that music can be made by hitting stationary objects - and importantly - instruments, without the kind of precision we normal think of when we’re talking musicianship. So, careful planing, measuring, timing and even more planning, as well as a whole slew of takes, can indeed produce music and thus illustrate that what you described is quite possible.
You’re welcome for my doing the deducing for you.
If someone held the marble and hit the tone bars with it at the right time in the video that served as a good example, I could see a connection. Basically, I am asking if “A” is possible, and you are telling me that, yes, “B” is certainly possible.
Here’s an ad from years ago – looks real to me.
[https://youtu.be/Vv9s6nQl3Wk?si=6jXG46jsQ3C5_Doj]
Wow, that’s cool and I think comes real close to the OP’s requirements. Not vertical, but still, all motion is downwards. It’s still mostly just one ball hitting notes on the way down and not being recycled upwards like the other marble machines. And I think if it was CGI they would have improved the timing of the notes, to make a shorter commercial if for no other reason.
Here’s a couple more examples:
Mesmerizing marble run (Facebook video)
Both videos flat out say that the music is synchronized, and don’t claim that the marbles are making the music. I think the absolute perfect loop of the videos also give away their status as 3D art.
This artist makes a different kind of marble run, which is contained in a box. Neat idea but also looks like CGI to me. The marbles just don’t seem to fall right. Also they have this ridiculous one with rubber balls and rubber chickens which is clearly CGI so we know they have the skills.
This one here gets us slightly closer to being real but it’s not exactly what you’re talking about. The run is real, but marbles themselves don’t make any music. It’s just nicely synched up to a real song.
While not directly vertical, it is almost certainly not CGI and a lot closer to what I am looking for, erratic musical timing notwithstanding…which is what makes the original videos stand out as CGI in the first place, of course. Thank you.
So I guess the Farting Nun Organ is out of the question?
Naturalness aside, it is almost, but not quite the perfect example. 
This is more like, what if Rube Goldberg built a player piano?
I think the ‘erratic musical timing’ is an unavoidable consequence of existing in the real world. The wooden balls and the xylophone keys allow a certain imprecise nature to the timing of each note, something which would occur in any mechanical gravity-powered musical instrument, even one made from metal.
Especially, I noticed that the variability in timing corresponds to how much the ball wanders laterally on a particular board as it descends. It picks up only so much linear velocity from each step, and “wastes” some of it on lateral motion.
But that arrangement turned purely vertical, even suitably condensed to accommodate the higher falling speeds, would be formidably tall.
I think that you could probably make a track that constrains the ball’s lateral motion much more, and hence gets more consistent timing.
Intel made a real life version of Pipe Dream in 2011.
As a demonstration of precision of control, impressive.
But the “instruments” aren’t making the sound. It’s just synched to the soundtrack of the original animation. And there is at least one minor difference in implementation: the round xylophone is being “driven” by an aimed pipe below the notional “distribution funnel” rather than by the magic steering mechanism of the funnel itself.
An impressive demonstration, however, and a pretty food realization of an impossible imagining.
I think the “instruments” are making the sound; it’s just that some of them are electronic (but still responding to the ball impacts). But the cowbells and cymbals, at least, are certainly real.
Of course, the other major differences are that none of the instruments are narrow strings, and the balls are all just falling to the floor after they’ve done their job, rather than into precise funnels.
No, they’re not. You can hear the high hat open and close, but that plastic representation of one doesn’t open or close a bit.
Sure, it could be the system isn’t so much synchronized against a pre-recorded soundtrack as it’s using triggers to play samples and reproducing the original soundtrack. (Which is a different level of cool.)
But it’s not actually playing acoustically, the way the design in the 3D animation would imply.
Sixteen or so cuts with no evidence that it was just one big shot, also.
This isn’t an example of the specific instrument, but it does show how easy it would be to make one. This “awful” sound of a screw falling through a turbine engine is quite beautiful to non-turbine-engineers.
