Mini duct HVAC systems are a gift to remodelers. Snaking small flex ducts through existing walls, floors and ceiling is 100 percent less invasive than using standard ductwork.
If you haven't heard of these systems, this short video will give you an idea of what they are all about. You can also send a link to the video to your customers. They can see the advantages of these systems immediately.
Here are companies that make mini-duct systems include: