here are a few patents that may tell us something about how Conn made their tone holes
although I can't see anything specific about rolled tone holes - I'm guessing they were influenced by the rolled edges on tin cans and biscuit tins etc.
Technically it'd probably be possible to make the tonehole chimneys separately with the rolled rim and then solder it on, but they were presumably thinking in terms of speed of production.
what's intriguing is the adoption of various patented features of Conn saxophones by some european manufacturers - not just rolled tone holes, but micro tuners and the rhomboid shaped left hand little finger cluster on the 6M... I don't suppose we'll ever know why, except that they felt like it..
since neoprene was mentioned earlier in this thread, I'd just like to point out that neoprene and other synthetic rubber materials like nitrile and teflon used for gaskets and o rings all come in different hardnesses measured on the
Shore scale, so it's possible that a suitable material could be found for sax pads...
I think I've seen something about goretex pads for clarinets too...
Here's an article by a bloke who got a sax with pads made from closed cell neoprene rubber, used typicaly in skin diving suits
"Incredibly, these neoprene/skin diver suit pads from the 1970's have all retained their original suppleness, usefulness, and seal. Incredibly, thirty years later, none have needed replacement, and the pads work as well as when they were first installed, despite decades of regular playing and use "
he doesn't mention any extra sponginess, but he's only using 1/8th inch thick rubber on a card backing