The people that sold me that first relay enclosure have some cool bus bar's in their ebay store. I'm sure other sell them, but they had one with 5/16 bolts and another with 3/8 -
https://www.ebay.com/itm/132444261679 and
https://www.ebay.com/itm/132444387604
Kind of wish I had used something like this, instead of the single post I have.
It looks like batterycablesusa.com has them too -
https://www.batterycablesusa.com/lar...sbar-250a.html
edit: lol, their in your picture too....