Yeah thats what I was thinking… I am uncertain how to go about it.
You would need to make a mold from an existing part with a flange. Lay the fabric in the mold however you plan on doing that, but for the flange, add tows of material to pack it into the flange section of the mold. You can use rolled up fabric, or just pack in tows. I would think you would want some of the fabric of the tube to also be IN the flange for strength. Don’t just make a straight tube, and add material in the flange with no connection to the tube.