That sounds exciting Drew. I seem to recall Robo made some double deep sized frames, mine are 14.5” deep. Basically a deep + medium in size. Seems to be a good size for a brood nest for my queens; not too big, not too small. I haven’t had them go up into the supers to lay any eggs yet.
I used 2 plastic pieco foundations to create my jumbo frames. I believe Robo’s was foundationless, I can’t recall. The plastic worked great; just a little time consuming to make.
As Finski says, large frames can become very heavy if they are packed with honey (as opposed to brood). My frames are spaced 32mm apart in an effort to discourage packing big blobs of honey on the peripheral areas of the frames like the bees will do on standard deep frames. It has helped.
While a bigger frame than the queen will brood up sounds interesting, I’m not sure what that buys you? Honey weighs much more than brood so now you’re really talking some weight issues with 3’ frames. How do you extract honey from a 3’ frames? How do you actually lift a 3’ frame from a 3’ box? If my math is working right, that would require lifting the frames at least 6’ in the air to clear the hive box? Lifting a heavy weight that high is really going to put some strain on your rotator cuffs. I’m not sure my rotators would be up to the task :( How do you mechanically support some massive combs :? If comb falls out of a 3’ frame, you will have a huge mess and a lot of very angry bees :(
Again, I’m not trying to discourage your idea, I’m just trying to add some data to your decision making. What I like about my setup is the brood is (has been) isolated on 10 to 11 jumbo frames which allows for an easy inspection; just gotta inspect 10 frames. The processing of honey is just like a normal hive. I currently use mediums for the honey. From what I recall from Dadants books, he believed that Langstroth had the right idea, and maybe even the right size of frames for the bees of his era (1850s), but with the more prolific queens available during Dadant’s time, he felt you needed bigger frames to accommodate the brooding capacity of the queens.