Thanks for the comments everyone
Made some more progress today.
Learned that rigid duct is a PITA. Distance right, angle wrong. Angle right, distance wrong. Gah!
Learned that you need to wear your gloves
all the time. My middle finger
found a sharp bit inside an adjustable elbow. Blood has been spilled... ((dun dun dun))
Still need to tape all the seams (lots of air leaks right now) but I want to make sure the positioning is right first. Not entirely sure I'm happy with the Barley box, but I want to keep it small as the fan is only 450 cfm. I'll see how it works and then decide if I need to change anything.
My dog Bandersnatch loves getting in the way. I'm going to have to get a baby gate to keep him out of the room because he'll chase and nose anything that moves, hot glass or not.