3D printed cores

https://formlabs.com/store/materials/ceramic-alumina-4n-resin/

It's too expensive now, but may be worth keeping an eye on for the future. Any shape could be made. I wonder if it would be possible to entrain bubbles in it to make it insulative. If made to the order of foamcrete, it would actually use relatively little of the expensive material for a given size.

I would gladly contribute to a Kickstarter to see a prototype get made.

3D printers can print other materials than ceramic, from my limited knowledge.  There are house-sized printers that lay flat "cables" of some kind of concrete mixture to form dwellings.  Maybe designing a new type to specifically address the specifications of RMH cores would be a productive endeavor.  Surely it would not be as expensive as printing in solid ceramic.

Or, instead of bubbles, what about a sacrificial material that burns away to leave voids? A different resin, maybe.

Donna Lynn wrote:There are house-sized printers

That's in my town if y'all want more investigations. The houses aren't any cheaper. Matt Risinger is Austin local.