Been lurking for months - time to engage.
If the idea is heat radiated from a "mass", and if a steel drum is - as I perceive it - a fairly short lived element of the RMH, why not have the barrel replaced with stone (besides, my wife thinks they're too ugly!)?
If the metal pipes that are used for the exhaust gas are oxidized out in several years, why not use just a stone path for the exhaust gas.
And, if these metal parts need to be replaced after a few years, does that mean that these beautiful "benches" have to be torn up to put in new metal?
Thank you all for the dedication to this idea and forum.