I did. The low profile Broan Elite 36 inch vent fan that I installed can be configured to vent straight back through a 3 1/4"x14" rectangular duct or straight up through a 3 1/4"x14" duct. This rectangular duct is designed to fit completely within a 2x4 framed wall. My ducting enters the wall, and immediately turns straight up, proceeding up until reaching a soffit between the wall and an exposed structural beam. Inside the soffit it transitions to a 8" diameter round duct, turns slightly to match the roof angle, and continues through a hole I cut in the roof, where it is covered by a black metal roof vent cap. I found the local Lowes and even a local HVAC supply store to be unhelpful, and ended up having to order the needed ducting pieces from a couple of places on the interwebs. I don't remember where I ordered the pieces from, but in trying to find where I purchased them from I found an old Gardenweb post by me where I wrote: "I ordered the transition and roof cap from AirShack.com. The 3 1/4 X 14 inch, 90 deg elbow was really hard to find. I ended up ordering 2 of them and a 3 foot stretch of 3 1/4 x 14 inch duct from a different online location (that I won't name because they charged $41 for shipping for those three items) "

Thank you. No contract-but my long term trusted contractor recommended this place. Please tell me what I should be looking for with respect to binding and appearance of staples. Thanks for you help!!!

Stairs are a huge danger area. If you get it wrong you will have massive slip issues with both the dogs and the visitors to your home. If someone hurts themselves on your stairs and the insurance company finds out you installed it yourself, they can and will deny you coverage for failure to ensure proper installation. BTW: It is very difficult for dogs (or cats) to 'catch' COVID-19. Bats and weasels (minks, ermine, etc) are MUCH more vulnerable to it. An installer wearing a mask and the dogs kept out side while the work is being done = just fine.

Thank you to everyone for your input! I wanted to follow up just in case anybody else is struggling with the same decisions I was with a curved expanded bottom couple of steps in an old staircase. Despite some of the recommendations above, I did go with plaid and I absolutely adore it. So it can be done, but to get the lines to continue to flow in a consistent way took a ton of planning and hours of labor. But I love how it turned out. Thank you again for all the help And suggestions!