Re: Project on a miniscule budget

I don't know if the hole is blind or not but you should consider
starting with a round tubular electrode before going on to square
electrodes you could even start off with a drill! That way you have
less material to remove for the important bits. You could also use
disk type electrodes, essentially a little square of material on the
end of the rod, this will help prevent tapering of the hole.

One of the main problems will be changing the electrodes over
accuately and also ensuring they stay nice and straight.

Dare I ask what this is for?

Graham