Oh thanks all - it's lovely to hear what you think, because different people see things different ways.
Fireworks, thank you - I always use Superior's metallics, with Bottom Line in the bobbin. Never had a problem with them, even doing fmq.
Those 3 big cubes are constructed entirely from 60deg. triangles (81 of them, 242 different pieces of fabric), which some comprise of 5 separate pieces! And you're right, when you're putting each of them on the wall, until you've done about 16 or 18 it looks really weird. I drew up a plan on 60deg graph paper I printed free off the internet. Drew it up, colour coded every tiny piece and numbered each triangle. Then I wrote myself a "menu" of dimensions of each piece for every triangle with colour and width of strips required.
Even then, when I'd stitched 2 or 3 and walked to the Board, I couldnt figure out which way round they went without looking at the plan! And some of the big cube hexes also contain parts of the base OBW fabric too. You do make them in the same way, it just looks so strange because of course each pinned block is not a "complete" cube as the smaller ones. And when you come to matching seams when joining vertical strips, it's great fun!
So it is a slow process - but very satisfying.