First let me say that I am in no way a call maker. Only calls I build are in my dreams. Im only speculating here, but here goes.
I think aluminum over copper would be interesting for sure. It might have that metally nasty rasp that would drive them mad.
Some striking surfaces would be tough to use for a soundboard due to them only being available in one size. Example would be most pieces of crystal and ceramic. I don't believe Ive ever seen a ceramic or crystal call that is less than 3.5'' in dia and to use it as a soundboard would mean the main striking surface would have to be about 3.75 to 4'' in dia. and I don't think they make any calling surface bigger than a 3.5. All this could possibly be overcome if someone had the ability to custom cut their surface diameters to any dimension they wanted.
I have been wrong more than once and I could be entirely wrong about this one, if so, someone please correct me.
Assuming you could cut any material you wanted to however big you needed it what about using granite, marble, fiberglass, or something else totally off the wall?
