My favorite keyboard is my customized Filco, and the only thing I don't like about it is that the aluminum case is so freaking heavy. It sucks because it gives the board the stability and zero flex I want, but a modern TKL that weighs 7+lbs is ridiculous. But what can you do? You want that feel and stability you have a metal case, and aluminum is the lightest material cases are available in.
Maybe someone will make a carbon fiber TKL case.