i can't comment on that 'thread' i was tagged in, but the advice i can give your friend is he needs to lightly sand his controller down, put 3-5 LIGHT coats of primer. then about 5-8 (depending on the color he's after) of base coat. The final step will be a long process of 10 coats of clear coat and a light session of sanding between coats 7 and 8, then after s/he lets it dry and cure i would then... wet-sand the controller for a nice glossy shine and feel.
All paints for this process would be car paints (leather/vinel such as duplicolor.
Another easier method is using krylon plastic spray paint, but it's cheaper and wears off after a decent amount of play time (depending on how rough he handles his controllers).
If your friend needs a written tutorial and a list of parts tell him to feel free to add me as a friend and i can message him what to do, exactly. Step-by-step.
I won't however teach him any mods i've learned to do, ie: LED lights and cord replace