This is just a simple idea that I think would make the game better:
A type of metal canister that can keep liquids hot for longer than in other containers.
To craft, perhaps just extra metal, or plastic around a metal container?
It seems a little silly to me to store hot coffee and tea in a little plastic bottle, and the heat retention would be a bonus.
If it’s just a simple mug, two units of water/coffee/tea would be reasonable, with just a heavier weight than the plastic bottle, but if it’s a larger thermos, it could hold 6-10 units, like a canteen.
In a quality thermos/mug, a hot liquid can stay hot for almost a whole day.
So it’s really not a big thing, just a small bit of content that I think would be a meaningful addition to the game.
Given the morale bonus of hot meals, this would have a small, but meaningful impact on gameplay. If I was going to add yet more items to the game (which I feel should not be priority until work on other aspects of the game have progressed further,) it would definitely be this.
Even if it was just double-walled with a space inbetween for insulation, it’d be an improvement. I’ve got travelmugs like that with simple air in between, they don’t make things warm FOREVER but they do extend said temp’s duration. The vacutainer idea would also work for me. I’d considered them a likely candidate for ‘better to find than make’ item anyhow.
If you were to make this, it’d require a very high fabrication skill, a forge, and a good deal of metal, and even then it’d be a “forged thermos” not as effective as one you’d find in a coffee shop or office (both of which make good places to put this item, BTW)
I’ve made one! It mostly involved cutting up a winter boot with that silver lining inside the boot insulationfluff, a mug with a lid, and a bunch of duct tape. It did not work anywhere near as well as hoped, though for the grade 7 science experiment that it was, it did help a little. Just a little.
Mostly, we had to contend with it smelling like boot in addition to coffee.
Making a pressure valve shouldn’t be much harder than making any other precision machinery. Just need something that gets pulled towards the low pressure inside the container and forms a seal. Once you have that you just need a bellows to create low pressure at the valve outside of the container and you should be able to get moderately close to a vacuum. I could see something like that as a high-end craft. On the other hand, an internal combustion engine is not much more complex and those are not craftable… A simple insulated heat-proof bottle should be pretty easy. I am not familiar with nomex but some sort of foam or air layer between two sheets should extend heated time. The problem with air is convection… Although heat-proof containers are also an issue. Putting boiling tea in a plastic bottle is not exactly a perfect plan. I mean, you will probably get away with it, but still…