/diy/ - Do It Yourself

Welder anon here
The project is going well, I just charged the capacitor bank to about 4.5V and it threw some fat sparks, so at least errors from this part are filtered.
Now I'm stuck because I broke both 3mm drill bits I wanted to use to punch some holes in the MOSFET copper rails, and I need a way to isolate a top layer, which will hold the circuit, the MOSFETs and a connector for the arcade button/pedal I want to use to control the discharge.
Now a question:
When using the cap bank by itself I had problems by trying to solder nickel strips as them ended up stuck on the electrodes instead of the batteries I wanted to weld, so my question is: Is copper a good material for the electrodes or I need to use other materials such as aluminum or something that melts at higher temperatures?