You need what's called a "hood liner" and ductwork. Depending on where the duct goes, you might want or need a "remote blower". Depending on your cooking situation (e.g., if you have a big, pro-style gas range), how tightly sealed your house is, the local climate, and how strong your hood is, you might also need heated "make-up air". Current ideas about residential hoods is that they should be strong enough to pull all the steam and "effluent" (i.e., cooking particulates--what you can smell) away from the kitchen. This keeps the kitchen cleaner and the house smelling better. In order to have a good "capture area", it's recommended that the unit be a few inches bigger than the cooking surface on all sides, though for most people, especially those who don't have gonzo gas (gas has its own effluent, including byproducts of combustion and unburned gas), one the same size as the cooking surface is acceptable. People sometimes get away with smaller, but it doesn't work as well and isn't recommended.

Many of the top makers also make hood liners. That's the works, and includes the filters, fans, and lights. Trailrunner did a lot of research before she chose hers, and decided on Tradewind (I think). I mention it because it's not as well known a name.

Your cabinetmaker should know something about the requirements from his end (i.e., how to construct the covering). Your HVAC guy should know about the ducting and possible make-up air. You can get a lot of info if you search the Appliances Forum. There are rules of thumb for determining the CFM (cubic feet per minute) you need depending on the BTU of your cooking surface. www.theinductionsite.com has a conversion formula for calculating BTU for a hood over induction.

Good luck!

I finally purchased my hood after much confusion about what's available. I will confess, I don't care a bit about the hood as I rarely turn it on. The brands I looked at were Vent-a-Hood and Broan. What you need to go up into the custom cabinetry is called a power pak. It's also called a liner, but that could refer to the piece of aluminum that makes the machinery fit into the space of the hood. Some units you have to purchase the blower separately- some units come with liners of set widths and some don't. I found the AJ Madison website very helpful. I had to ask alot of questions at HD, Lowes and the Great Indoors before I found someone that really understood it. Glad that decision if finally made! Good luck!