Tim, just a thought that came to the forefront of my mind while
reading your last post in this thread:

But if the modeler can specify what he wants with drawings and

specs, and if the pattern maker can do a set of CAD drawings from that
and the modeler can see they are good, and then the pattern maker can
turn on his SL equipment to produce the masters, voila! <

Perhaps the next best thing to holding an RP prototype in your hand
would be to look at a 3D drawing of it rendered photorealistically and
with key dimensions called out. The Rhino 3D program I'm learning to
use appears to be an excellent tool. I bought also a sister program
called Flamingo, which renders Rhino 3D files photorealistically.
Gorgeous stuff (can't wait to learn how to use Flamingo).

(I'd better insert some STMFC content pretty quickly.) The other day I
mentioned an ACF 19k gal. mid-1950s tank car that I had been working
on. For example, were this to be 3D drawn, photorealistically rendered
and key dimensions called out in the "photo", and several views
presented, would this serve well enough for a modeler to decide
whether or not to order up a master casting?

Key point: When I draw a car such as this tank in 1:1 scale, I include
the modeling compromises. For example, the AAR Standard Center Sill
Section drawing found in the 1943 CBC shows a dimension thickness of
13/32" for the steel used. This thickness is less than .005" when
reduced to HO scale. Fragile. I would think a resin caster, at
minimum, would need to cast this item at .010" for basic strength. On
the 1:1 drawing, then, I would show this compromise at the HO size
scaled up: The thickness of the center sill steel would be drawn at
.87" (.010" x 87), not the actual 13/32" (or .40625"). The modeler
visually should see easily what the model would look like when cast.

It's occurred to me previously that with such precise drawings, resin
manufacturers could approach groups such as this one for vetting,
thereby minizing the potential for errors in the model.

The next step might be that a group project could be put forward for a
resin caster to adopt and run with; the caster would present 3D
drawings throughout the process for critiquing and correction by group
members. (Perhaps a resin caster might come to a list such as this one
and say, "Whatcha need?" Any resin caster who wished to get involved
with a group project could give it a try.) I would think a nice price
break would be due to any group member wishing to purchase the
product. Perhaps, though, such a group approach would prove to be
unwieldy and, ultimately, unworkable.

My personal circumstances and goals would make this group approach
possible eventually, I think. But, it might be that other resin
casters -- highly selective in what projects they choose to develop --
would want none of it. I am only speculating here, hoping to elicit an
opinion or two in response. (I do not know if this message will be
ruled on topic; if not, Mike, I apologize for posting it. Is the
content familial enough to the subject of steam-era freight cars to
pass inspection?)

Many -- most -- small-business manufacturers keep their plans and
their thinking close to their vests. I have been counseled to do the
same, and, for the most part, have done so. But, since I am a hobbiest
first (for better or for worse), I enjoy chatting about the subjects
that have appeared in this thread with my hobby colleagues here and
can only hope not too many folk here have been put off by such a
specific production / manufacturing discussion.

Thanks much,

-Brian

Brian Chapman
Evansdale, Iowa