I emailed Brandon some months back, and he replied back to me. I game him an idea for a metal in my email, and he suggested I post it on this forum. This is what I said:
"I was thinking another cool metal would be to be able to talk to Preservation, and its alloy to be able to talk to Ruin. I know that either can sort of talk to you, but you cannot reply back, either does not know what you are thinking."
And Sanderson's reply (regarding metals) was this:
"As for the metals, I do intend my readers to speculate and interpret the metals uses. There has been a lot of discussion about this on some forums like The Time Waster's Guide. However, I am writing a sequel trilogy to Mistborn someday...
You have an interesting idea about a metal affecting Ruin and Preservation. You might add that to one of the discussions on a forum or on the Mistborn website to see what others think about it as well."
So, there it is. What do you people think?