Metal cabinet speakers

@Kenjit...I promise you the differences are not subtle.  

One other note.  What will be completely game changing is when graphene comes available as a skin.  Stronger than Carbon Fiber, graphene layers over a nomex or aluminum honeycomb will be at a completely different level.  

Graphene could be the holy grail for cabinet materials.  

How about concrete?  You can get the stuff they make concrete countertops out of at a store near me for around $15/bag.  Past a point it seems it would make more sense to have portable forms and pour the box onsite.  Or have the box made out of interlocking vertical layers that stacked on top of one another.  How inert and resonance free would a box be if it were brick and you just had a brick layer lay it in your listening room?  It wouldn't cost much.  Maybe have a light box and cover it in a thick layer of concrete.  If performance were really the point of these ridiculous boxes there are bound to be a lot of better ways to going about building an inert box than spending 120 hours machining aluminum.  

The thing is, past a point it can't possibly make sense to have the entire speaker delivered to a house.  You can do a lot of things for 100k, let alone 500k, that you can't for 10k.  It's a very different situation and calls for a different approach.  Or it would, if performance were the primary consideration.

Concrete is interesting but you need to create a mold for a hollow concrete box where you are going to have metal lathe running through it.  Concrete won't hold together without it.   

Not to mention that mounting hardware would be difficult. I doubt that a hammer drill will work near the edges of a round hole like that without fracturing off.  Maybe it would.  I am not sure. 

This seems like it would be harder than you would think.  That being said, a company did launch a speaker that has a stone cabinet and evidently it sounds great.  Acora Acoustics makes their's out of black granite.  

They are about midway down this article.  You can see mine a bit further down under Verdant Audio.  

http://www.theabsolutesound.com/articles/axpona-2019-andrew-quint-on-loudspeakers-under-20000/

The entire box doesn't need to be made out of concrete.  You could make the baffle from aluminum or some other material that is practical.  My point is that making the entire box of a ludicrously expensive speaker out of a single material is ridiculous.  Making it in a factory and shipping it somewhere is ridiculous.  It doesn't translate if the point is to get the best performance for your $685k.  What is going on here is that the guys who make the decisions for these companies have been around enough rich people to know just how vulnerable their vanity makes them.