I finally decided to pull the trigger. I've had my dust collector for almost two years but haven't hooked it up to anything. It was just a glorified vacuum. So it was a clumsy build, but I hope to refine it as I go...
Where I started
I purchased 40 feet of 4" PVC.
I did the rough cuts with a Japanese pull saw, but cleaned up the end with my band saw.
I was short some fittings, but I wanted to complete a run with what I had on hand. Took me quite a while to get a layout I liked.
All the way down to the lathe. Again, this was an "Add, Remove, Reconfigure" process. Total time for one run and my RAS was about 4 hours.
Now I know what additional fixtures I need and how to complete the second and third runs. I've still have quite a bit PVC left...