Designed a 3D model of the ATH-M40x/50x Earcups in Fusion 360 to be printed and allows you to customize your headphones. In my design, I have removed the locking mechanism for the 2.5mm cable as the cable holds very tightly even without it. Have not been tested on an ATH-M50x yet, but should work fine. Do let me know if it doesn't though and I will make the necessary changes.
The author marked this model as their own original creation.