I agree with the other two posters. Get some thin 3M tape from an auto parts store that also handles auto paint. It comes in varying widths, but it is perfect for this situation because it will show less of a line than the standard 3/4 inch masking tape. You can spray the body color right on the chrome or spray a very thin coat of epoxy paint on the chrome for adhesion before spraying the color coat. I did this on my 190SL almost 20 years ago and the hubcaps still look great. Time consuming, but rewarding.

Tom

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1993 300TE
1984 300D
1984 300SD
1976 BMW R90S