Got a small stain that will not come out because of the uniqueness of the interior...any suggestions? I am thinking perhaps a grey colored pencil..

thanks in advance...

 

go to auto parts store and buy a can of "tough stuff" spray it on let it sit about 30 secs and rub it off. I had a coke can EXPLODE all over my ceiling, had to let it sit, swore that stain would never come out it was there for about 4 months, and i was introduced to this sdtuff. well I'm a believer now. 99% of it came right out first try.