I've run 6" S&D up to each of the machines. I've tried to plumb the
S&D right up to the self-made 6" ports, but getting all of this to fit
together is not trivial. I'm thinking of plumbing the last 2 to 3
feet with a flexible pipe of some sorts. These are stationary
machines, I just want to use flex to simplify the connections.
Airflow-wise is good quality 6" flex hose better than say 6" flex
aluminum HVAC pipe? 10' of HVAC is $10 at a shop 2 miles from here,
10' of host is at least $50 via mailorder.

I'm familiar will Bill Pentz's site. That is where I got the
inspiration to even try 6". It's not been bad at all, but the flex in
the final 2 to 3 feet will make it much, much simpler. Bill replied
to my email and said he uses 6" flex hose, but noted his tools are
moveable. In my case it's for the TS, Jointer, MS, and DP, all of
which will be stationary.