Bondo Metal Reinforced Filler is easy to use, yet exceptionally strong for repairing and rebuilding metal, and fiberglass. Additionally, this filler is unique in that it can be drilled, anchored or tapped.Bondo Metal Reinforced Filler is easy to use, yet exceptionally strong for repairing and rebuilding metal, fiberglass and more. Reinforced with aluminum, this filler mixes quickly (hardener is included), cures fast and stays very strong – it won’t rust, and it can be drilled, anchored or tapped for non-structural repair. It has a metallic appearance, great for a range of uses.