That Landshark looks sick. I'd love to fondle one in person but for now I'm gonna peruse their website. As for drillium: sort of...
There are holes in the headtube and both BB shells where the other tubes meet them. They aren't as big as they can be so I had the engineer use a sharpie to outline the largest he thought they could safely be made and I put'em on the mill. Our frames are engineered to stand up to heavy couples with a rack and bags so with that in mind and the fact that we'll be a sub 300lb couple with no bags and only 3 bottles I butted the headtube and increased the butting in the BB shells (again, to the engineer's specs). I shaved the rack eyelets off the dropouts, won't be putting a disc caliper mount on the chainstay, and not installing the upper captain's bottle mounts. I'm using the carbon seat stays that lack V-brake studs* and did some cutting and shaving on the cable guides. I went though the piles of tubing and selected the lightest example of each tube (even though the variations were pretty small it adds up to just enough to be worth it). I'm gonna make the chainstays around 16.3" instead of the usual 17" and finally the seat tubes will be an inch shorter than on a normal large since the carbon seat posts I have are really long.
End result? I'm hoping for sub 2700g which would make it the lightest road tandem frame I've seen that will fit a 6'2" captain and 5'10" stoker. We're gonna be a climbing force! Now if the longshoremen would quit it with their "work slowdown" and get back to their overpaid job of uncrating my chainstay tubing I could get this built before our January Arizona rally. At the very least I'll be riding it and lending it out (to light teams) at our Mississippi River tour in April.
I did the math and it looks like using our carbon cranks and Shimano Octalink BBs leaves 520ish grams on the table that a set of Lightnings would take off. However, those Lightnings would have to come out of my pocket so it's probably not gonna happen. I may have to settle for a 22lb tandem that's custom fit and specced for me, first world problems
*The large Beyond frames I weighed (they ranged from 2930 to 2960) all had Ti v-brake stays and disc mounts so I guess the kind of frame weights factories usually claim would be for a medium, carbon stay, non-disc frame. Probably 2750ish?