I dont know if this is a stupid question, I tried to search but didnt find any help.

Basically what I've done is I've made a face to mount my turbo timer where the coin holder used to be. I've cut the shape perfect but when I cut the slot for the turbo timer I slipped and theres a scratch across the plastic (fairly deep too!) This is the first time I've tried something like this and I have no idea how to cover/fill the scratch or even the best way to paint it. If I spray it black the scratch will be visible..so what's the easiest and best fix for this?

please help!