I know the resin+Carbon fiber combination usually make a soft surface, with friction, the surface is easy to be damaged.
However, if I spray some coating on it after finish, can the things be changed? Is there any coating like that?

I am not aware of any "toughened" coatings you can apply to the resin to make the surface tougher or harder.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

Thanks