ATM eyepiece barrels? (1.25", filter threaded)

[akkana@best.com (Akkana)]

I have some old eyepieces (Cave Orthostar, vintage about 1976) which I use
often but which don't have filter threads.  Since they're great planetary
eyepieces, it would be nice to be able to use filters with them.

The "heads" of the eyepieces unscrew from the barrels; the heads are
threaded on the outside with something very close to filter threads, but
not exactly the same (slightly finer, I think).  I.e., I can screw the
eyepiece head, like a filter, onto the bottom of a normal, filter-threaded
eyepiece barrel a few millimeters until the threads jam.

I'm wondering where I might find threaded barrels for these eyepieces?
Ideally, I would love to get something that's threaded on one end for
filters, and on the other end for whatever this thread is that Cave used.
But I'd be relatively happy just to get a couple of 1.25" barrels that
are threaded for filters all the way down.

Who sells 1.25" inside-threaded tubing?

        ...Akkana