What products are available to get a dryer vent built in a 2x4 wall (new construction) and piped down through the bottom wall plate? It is an interior wall over an outside soffit below, and we can frame so the plate has no beams or joists immediately below the subfloor.
I see the "dryer box" product made for a 2x4 wall, but its duct opening is oval. Typical dryer vent duct, flexible or not, is 4" diameter.
We typically transition from 4" round to a 3" x 6" rectangular duct inside the wall, and back to 4" again to exit through the jack. This is a simple custom detail. You have a few options aside from this, but the important thing is to keep the cubic inch volume the same or slightly larger when you transition between each type of duct, and to keep the bends and length to a minimum.