Encountered these miniature wood marble runs in Switzerland. Still on my “wish list.” Sounds like you may enjoy them, too.
I dabble in furniture, which means I’m looking at baltic birch plywood, at about 40 euros per square meter of 15mm 11-ply sheets. At that pricepoint I might as well buy actual hardwood lumber.
As an aside, there's an app out there is an app for the iPad called "Cuboro Riddles" which is a "how do you make the marble go from here to there using the blocks." Given that there are multiple ways that a block can channel a marble, this is a tricky one.
... and then if you get this over into the lego domain (not as "just something to fiddle with..." it gets you into the GBC. There is a standard for how one connects to another described at https://www.greatballcontraption.com/wiki/standard ... and then at lego conventions people hook them all up. https://youtu.be/avyh-36jEqA