Welded together would be better.

Nah that's e6000, it dries more rubbery than superglue

Because OP uses their Brain in unusual ways.

Likely using dictation on an iPhone with "Penny" in contacts.

Look, you either keep these kinda thoughts to yourself, or expect me to politely ask you to indulge deeply all of your brain topic dump tendencies.

So how about them ackshuallies?

AKSCHULLY I'm gonna need you to tell us those

Do tell us !

For most of them, yes. But if you get old enough pennies, they'll be pure copper.

However, it's easy to tell just looking at this that many of these pennies have the newer design, so they're definitely only copper plated.

Brass?

Solder is mostly tin, sometimes combined with lead. It would melt the very second you put it on the stove.

Depends on the year, no?

The orange is called "flavor spots"

Yes it would. Adding material generally makes thermal conductivity worse. There is no material with negative thermal resistance, so adding more will always increase thermal resistance by at least a bit.

The only exception is 3D geometries, where an increase in surface area due to the extra material can outweigh the effect of the added material, and lead to a net increase in thermal transfer.

This can lead to a paradoxical effect, where ADDING insulation around a pipe leads to HIGHER transfer than with less insulation material, because the added material increases the exterior diameter, and therefore surface area.

(Heatsinks are also a good example. It is more material than just the component by itself, but increases surface area by such a massive amount that it more than outweighs the added material)

Copper pans exist but they can be a pain to cook with. The high thermal conductivity means they heat up much faster than you expect, so it's easier to accidentally burn stuff, and they also cool down much more quickly once off the heat which can also be annoying. Plus you need to worry about oxide formation and food sticking much more than you do with steel pans.