I've read of a couple that dug a huge hole with bulldozer.... then dropped 2 shipping containers and buried them back up... cost like 20k... mostly for the welding done to connect the containers, add rooms and windows... being impacted by earth is a natural insulator... and it faces south... I'd love to do something like this... team up buy land then place yurts and things while we build earth bag or container homes.…
MIG welders are a few hundred to own and backhoe rentals are about the same to rent. Did they have to pay someone else to do the work? Also, gasses like xenon are heavier than air. Do you know how they handled ventilation?
I think they had someone w/ some engineering skill do it, so it was structurally sound and all... I'm not sure if this is the exact same one I saw, but it's similar enough...