New octahedron piece

This is sort of a follow up on a post I did in January.  In that post I showed and talked about a necklace I had made in which I built octahedrons sized so that adjoining faces were almost at right angles to one another.  Each oct had a "waist" made of 2 short ( 10mm) tubes and 2 long gold filled tubes.  The angles weren't quite right angles because the 25mm gold filled tubes weren't quite long enough to be hypotenuses.  That would have required tubes of about 27mm, and I like to use stock sizes where I can.  So  on the sides of the piece the octs zigzagged a bit.
  In that post I mentioned wanting to use this idea to make a piece that was something on the order of a tic-tac-toe grid.  When I started to do it with the zigzagging rows of octs, I found that the intersecting rows weren't quite at right angles to one another.  To get that, I really did need octs that had right angles between their faces, so using the same 20 mm beads on the non-waist edges, I really did need 27mm waist tubes.
  It turns out the perfect solution was to use a 25mm tube with  a #11 seed bead at each end.  I wanted to use my anodised aluminum tubes instead of the gold filled ones, so that each chain of octs would have a different color, and I've found that with the aluminum tubes I'm pretty much always happier if I put a seed bead at each end of the tube.  That's because the aluminum tubes are quite a bit fatter than the silver ones, and so the open hole at each end of the tube is unattractive.  The addition of the seed beads solved both problems.