Particle size for filling resin with metal powder

[curious aardvark]

what is the point ?

It won't make the resin stronger and unless really really fine powder it'll just settle to the bottom of the resin.

I don't see any practical usage for this.

Also the metal powder will reflect the light/uv and either cause unwanted curing or insufficient curing in the right places.

Just don't see why you would bother :-)