Made of 3/8" birch plywood, stained a medium brown color to match existing kitchen cabinets.
We had a very good, but very old cooktop that was in need of replacement. This was a downward exhaust version, with nothing above it so we needed to replace it another downward exhaust cooktop. After researching models and finding prices, we ordered one and decided to install it ourselves. How hard could it be.
The installation wasn't really too bad, except for having to get the cutout exactly right and the awkward lifting it into place. Ok, so the installation was not exactly easy, but at least I know if was done right.
The main problem with the downward exhaust cooktops is that the space you save above the cooktop you lose below it since the air has to vent somewhere. In this case, it vents down through the cabinets and into dusctwork below the slab floor (and out to the side of the house). Previously, we just crammed whatever was needed into this cabinet, often banging up the ductwork. Having read the instruction book carefully, I found out two things that worried me about what we had been doing. First, properly venting the cooktop means having the ductwork not only very well sealed, but also free of any small bumps and other irregularities that would cause turbulence in the ducts. Second, you want to maintain a healthy clearance from the underside of the cooktop due to the heat.
Since we put in a lot of effort to properly duct the cooktop, we wanted to protect the ductwork from the day-to-day banging around. Also, the thought of something under there causing a fire worried me so it would be good to have something prevent that from happening. The solution was to make a custom insert that would protect the cooktop and ducts, but also allow us to maximize the use of the cabinet space.
This was a very custom made shelf since it was meant to maximize the space it allowed for storage. Each piece needed measurements taken directly from the cabinet, and it wound up looking like an abomination when just viewed by itself: crazy geometry, and lack of finish on the non-visible parts. However, installed, it actually looks very nice and does the job admirably.