Hello,  In reference to the Teflon bushings in Steinways, I was not
suggesting a separate rubber elastic component.  What I had in mind
was an elastic part of the Teflon bushing itself.  A molded part of
the design that was free to flex.  The best example I can think of is
the nylon bushings that are used to hold copper tube isolated from the
wooden studs.  They have thin flexible webbing that holds tightly to
the wood.

There is absolutely nothing similar about the function, I'm just trying
to suggest something common for reference.  I am not an expert on
plastic parts production but I do think that better precision is
obtained on internal surfaces by subsequent machining operations.
Cores can produce less than perfect surfaces unless very carefully
controlled.

Machining can produce almost any finish desired.  White Teflon can be
molded or machined to very accurate tolerances, but it does not seem
like the ideal material for this application as it is difficult to
machine and would probably be more expensive to get right than more
suitable materials.  I have heard that trying to ream the bushings by
piano technicians was very difficult.  Too tight one second, and loose
and clicky the next.

Best regards,
Spencer Chase