1971 Honda CB350
We de-badged the gas tank and filled the space with some fiberglass-reinforced filler. We also decided to repair the dent in the left-hand side of the tank this way rather than to attempt any metalwork for fear that we may open up some pinholes in the tank.
Once the base layers were built up we switched to standard lightweight filler to even things out. After the filler was compete we sprayed the tank with high-build primer and sanded smooth before putting down self-etching primer and getting ready for paint.