Harry,
The first thing that comes to mind is an appropriately sized 'heat-
shrink' type tubing. Of course, that assumes that you can find such
an 'appropriate' size and that it will 'shrink' enough. I have no
idea if there is such a size or not.
Another one of those 'off the wall' ideas is to use the stuff
that's used in casting small parts in the R/C model hobby. It's a
'rubber-ish' kind of stuff molded/painted around the part, then pealed
off when cured and used as a mold for a new part. Don't ask me, I
have no idea what it is. No metal content that I'm aware of.
And then, I guess you could always fiberglass it?
- 'Doc