Used a dremel on mine, with the flexible extension.

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If you use the tube-type sanding attachments, its quite easy to hold it horizontally and skim over the surface.

Of course, doing the insides of the wheel nut wells is rather easy, too.

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I spent about a weekend doing mine.

I went down to bare metal with the dremel and then sanded by hand with finer grit to flatten it nicely.

It doesn't need to be REALLY flat: once you've primed, sprayed

(powder-coated) them, all the little imperfections get filled in.

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A nice coat of polyurethane lacquer on top, and jobs a goodun.

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Ultimately, it depends on what colour

/ finish you're going for, though?
If you're for a satin silver factory-style finish, it'll need to be smoother.

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.as usual, good prep is the key.

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