If you choose metal containers because you think plastic is bad, remember that all aluminum food and beverage cans have plastic liners which usually contain BPA or other endocrine disruptors.
"Based on FDA’s ongoing safety review of scientific evidence, the available information continues to support the safety of BPA for the currently approved uses in food containers and packaging."
BPA in infant formula and bottles is banned for safety reasons in the EU and Canada. So, would you mind if I believed the European Comission or Health Canada instead? Even in the US, BPA is not permitted in infant formula and bottles in an industry-voluntary way that avoided the FDA making an explicit safety judgment on the levels of BPA present in the containers. The CDC warns against storing breastmilk in BPA-containing plastic.
BPA is not the end-all be-all of endocrine disruptors, of course: there are other classes of compounds banned in most of the developed world with solid evidence of harmful effects, like phthalates. It would be useful to check various established OECD health authorities and reputable research before dismissing the danger of endocrine disruptors as "rumors spread by know-nothings".
https://www.fda.gov/food/food-additives-petitions/bisphenol-...
I hope you don't mind if I believe the FDA over a bunch of rumors spread by the same internet know-nothings that brought back measles.