The Model F plastic is something that I have been complaining about for years. There is a "skin" layer with texture on top of a shiny substrate. You can make this blend fairly well under a paint job, but I have never really tried to preserve the beige color in situ.
A black metal bottom pan is easy: mask off your label(s) being careful that your masking tape does not pull up the paper. I often cut a plastic rectangle the exact size of the label and let the tape extend beyond it just a couple of mm. That will also survive a quick wash in warm soapy water if you are careful. I mask any rubber feet or bumpers, you do not have to be too careful there if they are black. If they are cork, they need to be masked or removed and replaced. Naptha is good for removing adhesive residue, but it is hard on paint and plastic.
When the metal is clean, paint it black. I swear by Rustoleum and many products are combined primer and paint.
Glossy black looks better but magnifies all imperfections. Flat black is much more forgiving and still looks good.
