Something else that works decently is Blob Eliminator by Langka.com. You actually want the bit of a blob that you'll leave with the regular old bottle of touch up from Porsche. It is polished smooth to the surrounding surface after it sets. Will you get a 100% perfect invisible match on a metallic? No, but better then I at least have ever done just trying to fill in the chip.

I got it from Bravarian Autosport (It was originally for the X5 but don't tell my CS). There are likely other sources maybe even amongst the sponsors.

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Les