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Problem is making the knobs out of a product that can be plated and then finding a commercial place that will do 3 little plastic knobs. None around here that I know of but maybe Hemmings has a listing for someone that does it.

Caswell has a couple of products to precoat plastic to make them conductive which might fall into the categories or processes you mention. Add the plating kits that work with those products and cost is steep for everything needed.

I'm leaning toward making new knobs out of high temp epoxy. Have an inquiry out to Reynolds now if a product I was thinking of using would be suitable. The plastic I used on those in the photos can start to deform at a temp which a car sitting in the sun out here could exceed. If the product would work for the knobs, would the epoxy be able to be plated is the next question.

If the product would work for the knobs, would the epoxy be able to be plated is the next question.

I would think so, the processes I described were designed for use on double-sided printed circuit boards which were fiberglass-reinforced epoxy.
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"Plated" plastic is normally ABS, and the process is not the same as electro-plating metal.

I was at a plastics trade show and there are some interesting new things coming on that I intend to play with when time permits.

I thought ABS was the usual material for a lot of interior car parts. Was considering using the SmoothOn casting resin they say has properties very similar to ABS in case I went for the possible chroming. That is their Task 21 but it has a heat deflection temp starting at 144F. No idea what the real ABS is capable of handling. The stuff I used on this first set which was planned for the sand mold pattern is only good to about 120.

I'd like to use the urethane product because it has a considerably lower viscosity so easier to pour and pressure cast. Whether the knobs inside the dash would be shielded enough in a car where interior temps can approach 200 in full sun has me a bit concerned. Don't want the stuff to get so soft that it bends the sides out or pulls off of the switch. The epoxy when fully heat cured can go to 350 degrees and if only a room temp cure can go to 250. Any opinions??

casting urethane crosslinks, it's not like thermoplastic urethane. It won't remelt.
Heat deflection temperature is the temperature at which the modulus-temperature curve bends, not a melt point either. So urethane will cast a part. I'm not so confident on plating it. You would be able to stick a chrome foil to it, as the surface energy is pretty high

Worked some more on the AC knobs by making another set out of high temp epoxy. Either would look and work great if the knobs could be an ordinary paint color. Still no luck with a decent chrome like finish -- paint is not anything close to acceptable and the chrome foil didn't look much better. For the next step have ordered some regular rubber letters in silicone instead of using the deep reliefs. Will be experimenting with metal casting via lost wax process rather than sand molds.

Picked up the bumpers from the chrome shop this morning and put some relatively inexpensive rolling around radial tires on the wheels. The upholster has done a test piece of the blue fabric and beige piping so mounted that in the car for some photos. Have asked for some second opinions on the combination in another thread.

Here's a wild shot to investigate on chrome:
How do the CD (compact disk) mfg'ers coat the CD's with such a shiny finish??

IIRC, one of the How it's Made TV shows on CD mfg said the silver or aluminum reflective surface was vacuum deposited over the disc followed by a clear coat of something else to protect the surface. Opaque background then silk screened on the rear label surface. There is a place in Idaho that advertises in Hemmings as doing custom chrome on plastic but haven't checked with them yet. As another poster mentioned, the typical plastic that is usually plated is considerably different than that used for my castings.

Since the originals are metal I'm going to try the lost wax and metal challenge before that to see what kind of mess I can get into trying to cast them in zinc. On the first pattern wax casts I tried with the deep relief letters made of regular rubber I didn't get the wax very hot so as not to damage the rubber. It cooled before filling all the spaces in the fonts so the pattern wasn't usable. Ordered new labels using high temp silicone and regular sized fonts so I can get the wax a bit hotter and maybe it will fill better. If it doesn't work, the only investment is time and not much dollars and I can see about chroming the plastic but if they come out anything resembling an original in metal it will be an accomplishment.

Right now I'm more concerned about getting some opinions on the upholstery piping color. We are on hold waiting to see if there are comments or opinions on whether using the beige piping matching the headliner and windlace looks anything close to the original color -- or do we need to try for a lighter or whiter color next to the blue. I can live with the beige and it doesn't look as horrible next to the blue as I first thought it would but if it is glaringly wrong then need to take a step back.

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Hi Howard

With regard to the tan piping contrasting with the dark blue broadcloth, that was standard practice for the Custom Super Clippers. Every example I've seen of those over the years, both restored and original, with dark blue or green or maroon had the tan piping. Its very distinctive and luxurious, I love the way it looks.

Rolls-Royces in the '70's-'80's frequently had contrasting piping especially those in the Corniche convertibles.

Steve

If the photo is any example, you are going to have a beautiful interior, not to mention a beautiful car. Your adventures with your Custom has been providing inspiration for my '51 Patrician project.