Bondo isn't so bad to work with... but you have to work fast. After you mix up the Bondo and it's hardener, you only have 2 or 3 minutes to work with it before it sets up and becomes unspreadable. You learn quickly to lay it on thinly and quickly... too much means a lot more sanding and smoothing and dust. I find that using wet/dry sandpaper and a spray bottle of water keeps down the dust and makes the job easier. looking at the finished product is deceptive, so just close your eyes and run your hands over the work to reveal any imperfections. When happy with the result, a tiny bit of primer spray may also reveal any issues.
