Sure, instead of plastic filler, the old world way is to fill in rough and uneven spots with hot molten lead. Lead is soft and mallable and can be worked easily.
Right after I wrote that I began to wonder if this can even be done anymore? This might simply not be allowed anymore because of the horrible environmental hazards of lead.
Most bodyshops today use plastic fillers to quickly and evenly fill in particular low spots on a car body. If over used, they can pop off. If improperly applied or not covered completely, they are known to absorb moisture and accelerate rusting.
'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)