Short answers, pulled from the story.
The oldest archaeological evidence of copper mining and working is a copper pendant found in northern Iraq, dating to 8,700 BCE. Gold artifacts from the Bulgarian Varna Necropolis, dated to 4450 BCE, are the oldest gold objects yet discovered.
Gold occurs in nature as nuggets of nearly pure metal, requiring no smelting or fire to obtain. Its low oxidation potential (-1.50 volts) means it rarely bonds with other elements, so it can be shaped with nothing more than a stone hammer and anvil.
Brazing joins metals using a filler metal drawn into a capillary joint at temperatures above 450 degrees Celsius, without melting the workpieces themselves. Soldering works the same way but at temperatures below 450 degrees Celsius, resulting in a weaker joint due to minimal metallurgical reaction between the filler and the workpieces.
Modern metalworking is divided into forming, cutting, and joining. Forming modifies a workpiece by deforming it without removing material; cutting removes excess material to produce a finished part; and joining processes such as welding, brazing, soldering, and riveting connect separate pieces together.
Production of bronze was common by about 2700 BCE in areas where copper and tin could be assembled. Bronze was a significant advance because its combination of edge-durability and stiffness made it superior to pure copper for tools and weapons, and it remained the most capable material for those purposes until iron came into widespread use.
A CNC lathe spins a workpiece on a spindle secured by a chuck while a computer-controlled cutting tool is fed into it along x, y, and z coordinates. The machine can perform turning, facing, threading, boring, drilling, and knurling, and modern CNC lathes can also perform milling operations using driven tools.