Spot weld removal, best method/tool?

[SkidmoreGarage]

Just to pile it on, the Blair tool is great even on modern cars which use more exotic steels (harder), thinner metals, and engineered spot welds. It is a much better tool than the HF version. Mine hasn't broken any teeth and it's still very sharp.

Just center-punch and let the tool do the work. It isn't the fastest, but once you get the technique, it is pretty efficient and both panels are usable.