 The filler they used is 3M...  The filler they used is 3M Automix 5895, a two-part flexible epoxy adhesive designed to repair TPO plastics. TPO stands for Thermo Plastic Olefin and is what many bumpers are made of. Our Crown Vic bumper is actually made of urethane, but this stuff worked just fine. The filler comes in two tubes. Squeeze out an equal amount of gunk from each tube and mix together thoroughly but quickly. It dries to the touch in only five minutes. |  Auto body class instructor...  Auto body class instructor Brian Ferre spreads the filler on the same way you'd apply Bondo. For big repairs, use small amounts of filler and build up in several layers, allowing the stuff to dry between each layer. Don't try to fill a giant crack with a huge blob of filler-it's gooey stuff and won't hold its shape as it dries. The filler is ready to sand in 15 minutes. |  Begin sanding with 80-grit...  Begin sanding with 80-grit paper on a sanding block to knock down the high spots and rough edges. If you need to add another layer of filler, clean the area again with adhesion promoter. Students Donald Smith and Raymond Anderson watch as Ferre shapes the filler to match a contour line in the bumper. |