FWIW, Ritchey used this construction on his top of the line MTB framesets: the Annapurna, from the early '90's. They were fillet-brazed, then filed to look just like a lug. Don't say it can't be done, or why would anyone...... otherwise one starts questioning most endeavours that are not purely functional. Neill Currie Deering, Nh........just back from 3 glorious days on the Cape, with bike, just a "simple" fillet-brazed item.