it would be great if you could design your own lugs and get them cast. I don't think that anyone will start a business like that, but you never know. It does seem like it's something that can be done, but the bike industry probably wouldn't support it. So it would have to be a more general application. Like Doug implies, there probably would be a fairly extensive learning curve to get the lugs to come out right.
There are a lot of people working on 3d printing using welding. The stuff I have seen leads me to believe that a lug is not a great application for that, but it might be in the future.