You have to stop modeling forever. Never again can you cut, glue or paint anything resembling plastic.
Perhaps leaving the contry would be a good idea.
Naaa, just kidding. Missing plastic parts is a royal pain in the b...
I hope you will find your missing part or get a new one.
years ago I lost an airfilter, for a 440 cu. chrysler engine. The car looks finished and has been on display for years, but to me it is never finished. everytime I look at that model, I always think of that

airfilter.
Good luck in finding your missing tail light.