Inlay Metals

[Kentucky Colonel]

For inlays, I have seen silver, gold, brass, and iron. Am I missing anything? 
What about pewter?

 

[Muley Hunter]

Pewter for a nose cap. Not an inlay.

 

[Smokin' Joe]

I don't know all the different metal types used for inlays beyond what you mentioned.  I do know there is a difference in the "quality" of parts manufactured/sold.  I made a rookie mistake, I didn't have my drill bit aligned perfect and drilled a hole in my brass side plate off center.  I ran over to Track Of The Wolf and purchased a replacement.  The replacement plate was not nearly as heavy duty, much thinner, and not polished like my original.  I was disappointed to say the least.  Of course, once mounted and worked over you can't tell the difference just by looking.

 

[Kentucky Colonel]

Have you even use alternative things for inlay? Like, metal lapel pins, tie clasps, coins, and kilt pins? 
I ask because that might expand the options quite a bit. I have been looking at some heritage inspired 
options that are not commercially represented, but would not be out of place on a rifle.

 

[Muley Hunter]

I think it's a personal thing. It's your gun to do as you please. Inlay anything that appeals to you.