You have to be careful with either plastic or aluminum.  I used a similar aluminum locking box successfully for years; it even worked after it dented.  A rigid plastic container cracked with only modest use, while a more flexible plastic sandwich box is still useful a couple of decades later, after a lot of use..  The great thing about aluminum is the ability to heat water over a flame, something not possible with plastic, unless you use a stone boiling technique.  I wonder, has anyone tried to heat water in a plastic container using hot rocks?
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Geezer in Chief