By Dave

<< It would be very difficult to accurately cut the final joint on the ends of the beams and I don't think there's enough surface area to to make a strong joint. You'd need to add some sort of plates top and bottom, I think, to hold the beams together and then I would guess the joint on the end of the beams is unneeded complexity.

<< I think the joint could be assembled but keeping it assembled would be the challenge.

<< As for sources for joining more than two pieces of wood like that, you might look for Japanese joinery techniques. there's a lot of stuff on the web about it. It's not very common in western woodworking and carpentry to put pieces of wood together that way and when it is done in carpentry applications (geodesic domes for example), it isn't really joinery because the pieces would get bolted through a common plate. The time required to actually create a joint such as what you've drawn* wouldn't be appreciated. In Japanese woodworking, though, that sort of work would be valued very highly.


* my Moi 3D Draw above ;)