To my knowledge, there are no metal 3d printers capable of printing a full scale frame. Lugs and maybe a tube, sure. Full frame, no way. There are plastic printers capable of very large scale objects (furniture sized).

Ti honeycomb type lugs could probably be easily bonded to stock CF tubing, so it's definitely feasible. The advantage of a honeycomb is that it would have significantly more surface area for bonding and likely more robust than a conventional bonded lug.

As mentioned above, 3d printing costs for metals are astronomical. Metal 3d printers are almost exclusively used for R&D type activities where the cost is folded into an overall R&D program. There are a few places using 3D metal printing for production, namely medical and aerospace (jet engines). If you happen to have access to a metal 3d printer, then it's totally feasible to print your own lugs...