I saw the video Lowboy. The thing is you can tune a harmonica reed plate in the open like that. If you remove the chrome covers from your harmonica you can see the reeds and they still play. The melodica is constructed in a way as if a harmonica was turned inside out. the air is flowing the other way across the reeds. I have thought of removing the reed plates tuning them and putting them back but most models seemed to be glued in place and I’m also not sure if all the re-seating will change the air-pressure.
I’ve thought of doing some sort of harmonica/melodica conversion where I’d run a set of tubes from the keys to the individual reed cells on a harmonica.
I’m not sure why a company hasn’t tried a harmonica-like design. I suspect the manufacturing cost would be higher?