Achieving better tolerance in the faces of a square pocket can be done, even though it would involve more machining and added cost. We are capable of accomplishing the task, depending on the quantity of the order and the tolerance desired.
To securely hold grounded electrode sticks in and out, and to ensure tolerance and repeatability of the corner, we have a good alternative in our V-Block holder, which you can see here: https://maxxtooling.com/en-gl/products/maxxmacro-vice-008458-v-block-holder-stainless