Hi, i have a fuel bottle that is similar to this: http://www2.towerhobbies.com/cgi-bin...?&I=LXLS14&P=7
, I have lost the little black cap. So what would you guys suggest to replace it ? I usually would fill up the bottle with fuel and store it in the locker room, the balck cap has done a great job sealing it, now I can't think of anything that can do the job, please help.