Gold coating on split test cells will help prevent rust and corrosion against highly corrosive electrolytes during the cell cycling testing. Even with gold coating, the electrolyte may slowly corrode the gold coating and expose the metal underneath. With the DIY kit, you may reapply the gold coating to extend the life of the split test cell.
Find this product from goldplatingservices in the intercontinental US/Canada or from your local gold plating provider.
Keep in mind that aluminum and titanium require industrialized processes to coat with gold.