An adapter that mounts in the Melzi holes and provides mounting holes for the MKS Gen 1.4 and a mosfet board.
You'll need to make a new hole in the case if you want to access the USB port on the MKS Gen 1.4 board. I drilled a hole and use a nibbler to make a neat square.
I printed this in PLA with 100% infill for rigidity.
You may want to use ABS since it still flexes a bit. It was a compromise between thickness and strength but seems to be a good combination.