@lowrider57 - many years ago when I first started looking into isolating my components I "created" my own low tech version of a foot using a steel washer and a hardened steel ball bearing - see...
http://image99.net/blog/files/0915f27ce41639dc6e4bf13bff2cbcbb-24.htmlMy thoughts were - I figured cone anchors the component to the shelf, even if the small protective disks were used to prevent the spike digging into the shelf - whereas the ball is less prone to digging in.
It did a great job of isolating the component from the shelf, but a lousy job of draining vibration from the component, because of the sorbothane
Since I now use a piece of granite under the component, using cone would have less tendency to dig in.
Fast forward to a couple of weeks ago when I started looking into "draining" and I thought - what if I remove the sorbothane and just used the washer/ball "foot" attached directly to the case of the component.
It does drain - e-v-e-r-y-t-h-i-n-g!
The resulting image was presented so far back behind the wall (i.e. behind the speakers ) it resulted in lower volume. I had to crank the amp to 1 o'clock (normally between 8 and 10 o/clock.) to bring the image back into the listening room But it was very detailed and crystal clear, it just sounded very far off. It also sounded quite "harsh" or "Brittle"
I found the wood cones have the same clarity and a warmer, but the image is more forward and as a result the listening level is back between 8-10
I have also tried the washer with a glass marble - this is very much better than the steel ball - it does not have the harshness or image issues
The Terrastone looks as though the ball is either steel, brass or ceramic (from the images on the web) - not sure what the body is made of though and cannot find any details - could be an alloy of some kind?
I've heard aluminum cones are very much like wood, but I have not tried any to date
Maplegate uses brass - like the Bear Paw,
I now have a guy turning some cones from brass and bronze in different sizes - fiigured I would give them a try, see which material provides the best sound.
Hope that helps - Steve