I was going to weld up some trim holes on the rocker panels of the cuda. My plan was to use some common nails and weld the heads into the holes and then cut off the nail. Never got around to trying it though.
The problem with that is the effort and time to clean the nails before welding on them.
Most nails are coated with a galvanized or blue oxide finish. All of that needs to go before welding because a good weld would not happen with those coatings in the way and welding on galvanized can produce a poison gas.
Maybe sand blasting the nails would help but it would be faster to weld fill small holes with the welder. I ran into that on the side trim holes on a 68 dart.