The cardboard tank is a kind of a moot point now since they no longer produce this tank. I saw one set up as a non-working display at a tank center in 1978 and had some of the same concerns. Here’s a timeline on their tank production:
https://www.samadhitank.com/samadhi-tank-models.html
NB: They say they opened the first ever tank center in 1979, this is incorrect as I floated at a commercial center on Spruce St in Boulder Colorado in Jan of 1978. Later there was a tank shop that opened in Denver in 1978 which eventually became Float-to-Relax.
I wonder when Eric Polcyn opened Spacetime Tanks in Chicago… just checked it out. He started in ’82 – https://web.archive.org/web/20070209101240/http://spacetimetanks.com/
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