This will show you how to remove scratches from nes controller. Is what you need is
P600 3M Wetordry sand
Polishing compound any of your choice
Step 1: Sand the Controller
You wanna do is to open the controller apart. Once you have the controller apart now ready to sand first. Let do the back cover first. You wanna take it slow and sand every part of the controller. The way I did it on the front cover was I sand the edge and on the black part I wet sand the sand paper and work around that area.
Step 2: Polishing Compound
Once you done sanding don’t forget to wash off the dirt using warm water. Now dry try it up. Now you can polish it and keep polishing until you like the results.
Sorry I rush on the polishing I need to go back on the front cover and polish it.