>"Would builders be open to using another's carved lugs?
>Would Richard Sachs..."

it's a good concept, but i don't see myself using it in practice.
i think the economic of scale of the "typical" builder is such that
the time it takes to do the work can be easily charged for, and there's
no distraction from the frame, as in, guy x made the frame and guy z
created the lug windows. if it was all done in house, i could see it
working fluidly; each worker on staff has his specialty. i see frame
making as the kind of task where control reigns; using parts that
others have had a hand in could be extended to cf seat stay assemblies
made by industry and all shades of grey in between. where does it
begin. where does it end.
your kilometers may vary. wink.