I have several PTC heaters too. The post is really just an example of a straightforward application. I would actually like to try building complex automation using mostly simple base materials and where time is not the primary constraint. Like what complexity is possible using only an automotive battery, a small solar panel array and household recycled waste. Like one idea is to make simple composite tiles from cardboard, rice/wheat glue, and aluminum soda cans. So the quest would be to create a machine that only needs a rough stack of random cardboard, a container of discarded cans, some rice or wheat + water, and something like old thrift store silverware/cutlery or any source of recycled cheap steel.

I'm most curious about a mindset like in situ resource utilization. So how might a machine manage power to maintain itself, like sharpening its own tools and maintaining itself as much as possible to take simple inputs and create a required output.

The nichrome wire is interesting for its broad range of applications, except for how to form it in situ. Like if you had a robotic arm and nichrome wire on mars and all you need to do is make a heater for a special shape of object, it would likely still be a large challenge... Unless there is some easy methodology for forming the heater wire.