Cast covers might offer more rigidity and they look cool:
http://www.wallplatesonline.com/p/95334-Cortina-Stone-2-Duplex-Outlet.aspx?gclid=Cj0KEQjw5YfHBRDzjNn...
Stone wall plates above with some foil and damping on the back look interesting.
https://www.amazon.com/Amerelle-94DBB-Continental-Wallplate-Brushed/dp/B00FWWE2OG?th=1
Cast brass might be rigid enough
https://www.walmart.com/ip/Amerelle-94DDN-Continental-Satin-Nickel-Cast-Double-Duplex-Wallplate/4743...
Cast Nickel might work
Haha, Cast iron available, but that would be magnetic. I'm going to have to check out some examples at the local stores.
http://www.wallplatesonline.com/p/95334-Cortina-Stone-2-Duplex-Outlet.aspx?gclid=Cj0KEQjw5YfHBRDzjNn...
Stone wall plates above with some foil and damping on the back look interesting.
https://www.amazon.com/Amerelle-94DBB-Continental-Wallplate-Brushed/dp/B00FWWE2OG?th=1
Cast brass might be rigid enough
https://www.walmart.com/ip/Amerelle-94DDN-Continental-Satin-Nickel-Cast-Double-Duplex-Wallplate/4743...
Cast Nickel might work
Haha, Cast iron available, but that would be magnetic. I'm going to have to check out some examples at the local stores.