I keep trying to rotate (orbit) the pictures for a different view. LOL. I see you moved the duct out from the stepped wall. In that case the other end has some curves that may be able to be reworked. Keep in mind curves are bad on the SP and bad on the budget. The fewer the better for both. I was hoping the two branches toward the back of the shop could intersect along the wall to the right (DC side). Curve-curve or curve-curve-curve setups are also bad on the SP. The first drawing look as though they may be able to intersect near the back of the door way on the right side.
I agree on building stuff to just tear down later. But it isn't as bad if you already have the stuff on hand and aren't spending additional money to just throw away later. My phrase of late is "I don't have much time nor money. But I have a lot more time than I have money."
The duct is moved out from the stepped wall to avoid an obstruction (Garage door opener). I could (and probably would) straighten it out if I use an adjustable elbow, but for design purposes I'm staying with 45's and 90's.
D.
I finally figured out how to deal with sawdust in my hair.
I shaved my head.