It would be really cool if you could use a compressed air tank that you can recharge with a bike pump. Something like this has a max of 200psi and is refillable with a shrader valve. More upfront cost but but you don’t have to buy CO2 cartridges.
I think part of the appeal of the espresso maker this guy DIYed is that it has no pump/electrical components. Less points of failure and cheaper to make, cost seems to be a driving factor in his design. A bike pump is a fairly common thing for someone to own.
fourbardesign.com
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