I'm somewhat surprised by the price of the 3D printed lugs.
I've had a few things 3D printed in a material they call "stainless steel" and they were pretty reasonable. Much smaller, to be sure: a couple saddle badges (about $10) and one part for a Resilion brake (about $25). I had them "printed" by Shapeways.
According to the Shapeways website,
"Steel is printed by depositing a liquid binder onto a bed of steel powder one layer at a time. The product is then removed from the printer and infused with bronze. While the product is being transferred from the printer to the infusion chamber, it exists in a delicate "green state" which does not support interlocking parts." I'm not sure I'd call that "steel" but they do. So I guess your lugs would be "printed" by a different process? When Shapeways "prints" brass or bronze, they actually print a wax model that is then used for a lost wax casting.
I wonder if a "green state" print of a lug would be sturdy enough to be assembled into a bicycle frame. Brazing would (could?) then infuse the brass into the steel. I suspect this process, if it would work at all, would be different enough from conventional brazing that you might as well just learn to do it yourself.
I had this printed a few years ago in
17-4 stainless through Solid Concepts (now Stratasys) in a laser sintering process. I see they now have 316LI wanted a prototoype to test that I could possibly do a lost wax casting. The cost was ~$200 as I recall. The surface was fairly rough, it would take a significant amount of sanding and polishing to get that mirror finish you're looking for.
BTW, this is the decaleur I made with it:
This project has been on the back burner, I'll send it in to Waterford to see if they'd make it for me.