Hello Kevin, it is one solid piece of metal and it is flat. It curves up around the end that wraps up to the back of the keys with slots for the sound to come out. The end caps appear to be a hard plastic, the finish is almost a brush look and almost looks like wood but I would say plastic. I have never opened it and don’t know what to expect so unless it needs a tuning it will remain closed. This Melodica is in perfect condition. I will be back home on Saturday and I will try to find some time to record both the Professional and the Piano and post it. I think I am going to start using it more. Like I mentioned before I don’t know why I stopped playing it. its been in a box in my closet for at least 8 years and just took it out recently.