Many of the header boards come premarked for various sized doors so that you will know where to cut it for a perfect fit. Most pocket door kits are designed to handle a door up to about 125 pounds. First select the doors that you plan to use so that you know the weight capacity of the pocket door kit hardware required. The real fun will be selecting the doors. There are many attractive and unique-looking doors that are compatible with any of the pocket door kits.
Several manufacturers make beautiful natural wood doors from oak, cherry, walnut, etc.
For a contemporary look, some manufacturers offer decorative metal inserts or embossed metal skin doors. Instant Download or Rush Mail Order Update Bulletin No. I have heard that ducts from the furnace are a major energy waster in most homes. My sheet metal ducts look good to me. Close the register outlet to a room and then check the sheet metal duct joints for leaks.