Was just going to use some 50x50x4 or similar mild steel legs. My fuzzy recollection is that most stainless rods should be ok, as the alloying elements should dilute across the weld metal but I'm not sure. They also sell a 'weldall' rod here that claims to do everything except cast iron (but may be snake oil).
Any recommendations? Tips? Not a critical joint, but don't want it to be shamefull.
