More tetrahedrons

I'm playing with tetrahedrons again.  I'm discovering that being able to cut my own tubes is changing my mindset.  When you work with beads mostly you're saying "what can I do with the beads I have?"  When you can make your own you start to ask "What beads ( or in this case lengths of beads) will do what I want to do?"  I came up with a sequence of tetrahedrons that would produce a very gentle curve.  But by lengthening the tube on the outside of the curve you can make the curve sharper.  But how much to lengthen it?  I did what I could with math--Pythagorean theorem and all that.  But that doesn't completely do it because there's always some looseness in beadwork, and errors build up.  I had

decided I wanted to do a necklace that would go over your head without needing a clasp, but I didn't want it to be too huge either. And the tubing is expensive enough that I can't just keep trying different lengths till I get what I want.
   I played around with coffee stirrer straws (top picture), using 50mm straws for 25mm tubes, 40mm straws for 20mm tubes etc, and could approximate things that way.  For the most part I'd like to stick with cutting my metal tubes in lengths of 5, 10, 15, 20mm etc.  Otherwise it's just too hard to keep track of things.  But for a given piece I can always pick one element (like the tube on the very outside) and make it whatever I need to make the shape come out right.  Anyway, I'm still learning, still having fun.