Thanks, Mike.  This one has a pair of simple leaf springs to hold the
carrier in place under the condenser, so I'd expect the original
carriers consisted of two flat plates, possibly with a film width milled
slot for clearance and alignment pegs, of course, and likely some kind
of flange around the outer edge to prevent fogging from stray light.
Hinged or not, I don't know -- no carriers at all with it.  The lower
body has a tab protruding at the front of the carrier slot which has a
threaded hole that looks like M5; I have no idea what for.  The carrier
stage is circular, almost exactly 150 mm diameter, with a chordal
straight edge at the back 28 mm deep into the circle.  There's a milled
notch with a leaf spring in each end (secured by large headed screws
that probably also acted as stops); the slot is 5 mm wide and 5 mm deep,
in the head within the chordal rebate, about 3 mm behind the back of the
stage proper, which I also haven't identified as to purpose, though it
looks as if a 5 mm rod could be inserted from either end to a depth of
about 35 mm.

Minimum bellows length is 29 mm from the top of the M39 threads to the
bottom surface of the negative carrier stage; 28 mm lens might work
without modifcation, as long as I won't need huge magnifications.

The condenser is about 115 x 80 mm, and the bottom of the condenser
would be no more than about 6 mm from the negative, so it probably used
glassless carriers.

It looks as if this one might fit, at least by shape:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=29987&item=3815153023&rd=1

It doesn't look as if any of the Beseler, Omega, or Saunders carriers
listed on eBay will fit.

I surely can fabricate carriers to fit (though I prefer brass over
aluminum, because it can be soldered more easily) -- though it would be
easier with one factory carrier to look at.  It'd be still easier,
though, to buy some, especially with the fire-sale prices on off-brand
enlarging equipment on eBay these days.