Home made shunt resistor
The shunt resistor material shuld have a very low limit influence of the temperature and very low winding inductance. So the best properties of the material is the one with small temperture coefficient and high resistance (resulting a short coil) and off cource the required diameter.

Bellow is a table with sample materials and its main specs that is required to select and design a shunt resistor.



A welding electrode usually is made with a similar composition to the metal being welded (i.e iron or tungsten), making this materials one of the worst for choice.

The last column of the table is useful to calculate the thermoelectric voltage caused when the shunt resistor connected to the rest of the circuit (both ends of a copper wire or copper in PCB), which contribute to the total voltage drop.