best thing to use ...

whats the best thing to use to make a fuel cell for my 1/24 civic hatch? i would like to place it in the back ( not using rear seats ) and i would love to see a cell back there ... anyone got any good ideas?

I think styrene is the best solution. Basically you just have to follow willimo's how-to (http://www.automotiveforums.com/vbulletin/showthread.php?t=303021) to make something like this:
http://www.sandtler.de/katalogangebote/artikeluebersicht/fuel_safe/fuel_safe.htm

The other solution is detailmaster.

http://files.automotiveforums.com/gallery/watermark.php?file=/502/138187000fuelcells.jpg

The flat one is in Perry's catalog, the upright one you would need to ask Perry's about.

http://www.perrysresin.com/

and check out the showcase