Click on Image for FULL-RES
(All assemblies [dry-fitted], just about ready for casting, December 2010) Coming off the final weeks of 2009, this build was competing directly with ongoing Matt Stein Models projects for a place "under the rubber": the three hull pieces and conning tower all to be molded for casting in resin. That's a competition my personal-build projects will always loose, to the (themselves often backlogged) commercial priorities - and this proved to be no exception, throughout practically all of 2010.
That prolonged delay, however, gave me sufficient time to clarify/decide some key issues which had been straddling the fence for some time: 1) What, exactly, was the completion plan for the conning tower, and 2) Will these masters really be used to develop bona-fide, commercial parts for Matty's Models or not?
Regarding the first one, the decision to mold and the construction strategy leading up to it can be complex, depending on which features are best added before casting, and which will be best carved directly into the resin, after casting. In almost every case, however, overall proportions of the master have to be correct before casting in resin, and I still had nagging questions about whether the conning tower assembly was somehow
too long: 
Click on Image to EnlargeThis appearance despite the inserted length (white) having been explicitly determined based on a profile earlier traced
directly from a historic photo-reference. Originally, I met this concern with the casual idea that, if I ever did discover (how much) it should be shortened, I would simply do that by chopping- and pasting one or two (of many) resin castings back together into the correct proportions - however this would mean major loss/reworking of much surface detailing, whose addition was accordingly put off:
Click on Image to Enlarge Except for the remaining Nichimo details, note how bare the (silver-painted) master looked, at the end of 2009 here, with how it would come to look exactly a year later (see below).
12/5/10
While the extended delay throughout 2010 killed all building momentum, it did provide time finally to locate additional conning tower profile-reference pics (more than) sufficient to enable a definitive finding, resolving once and for all the question of whether the conning tower - specifically, the lower-AA "wintergarten" platform - was or wasn't correctly proportioned:

Click on Image to EnlargeAt left, against both of two, near-perfect side views at the Chicago Museum, the match (when fitted to total length) looks near-perfect. At right - though harder to make out - the matches against both a (thumbnail of a) profile drawing by
Great Plans (top) as well as against a greatly-enlarged, historical picture from her capture (bottom) appear likewise to be very close.
The above clearly confirms the original profile was good - and thus the master should be, as well - but
was it, really? I traced pics of its profile to find out:
Click on Image to EnlargeCompositing tracings from both the above side-veiws, I obtained the "average" profile, shown at bottom...
...and compared it against the original, working drawing:
Click on Image to EnlargeWhat was discovered was that neither the lower wintergarten, nor upper AA (machine-gun) decks were too short, nor mislocated, but the
forward conning tower was (slightly) too short. And the main discrepancy: the upper-AA deck was too low - a fault noted earlier in the unassembled Nichimo pieces, but expected to be largely corrected by addition of the machine-gun deck piece - obviously not the case, as it turned out. The forward conning tower would easily be lengthened (see below) - but at this point, the only practical fix for the upper AA deck is to stack additional casting(s) of it - so further proportioning of this feature must wait for availability of the casting(s).
12/19/10
However there was significant detail to be added, pre-casting, to the now-validated wintergarten - and here and there on the conning tower, as well:

Click on Image to Enlarge
FULL RES-----FULL RESAt left, surface-checked with silver paint, and at right, (re-)stripped back down to reveal its composition, note the conning tower has been greatly further detailed - particularly on the wintergarten, in the central area (white plastic) where its length had been extended. Note the upper conning tower proper has been lengthened as indicated, with strips of (white) plastic. Brass PE provided hand- and climbing rungs - the latter cut in-place from 240-scale, 2-bar railings left deliberately over-long, to provide for optional position-adjustment (removing excess from one- or both ends) by the builder, to match openings in the railings he supplies. And additional doors were added deliberately in the style of the existing Nichimo depictions - even though the latter are overscale, particularly their hinges, to maintain a consistent "look and feel" throughout.
This master is now absolutely ready for casting - and, with any luck, completion - in 2011, as are the 3 upper hull/deck pieces (not shown), as well.
Cheers,
-Matty