CF is light and durable. I think it was Serum who made a box for his batt tray out of CF, he said he was really pleased with it if I remember correctly. Try the aluminum, see how it goes.....if you don't like it, then you know where to go for the CF :)
"if you've got something to say, say it peacefully"
made my tray from some carbon fiber cloth scraps I had laying around ,depron foam and some good finishing epoxy...4 layers of 3.7 oz 80/20 cloth seems plenty thick .I made the bottom thicker with depron foam between the 2nd and 3rd layers so I could notch the bottom out for the mud guard nuts on my Cen MAtrix chassis. There are a couple pics here http://www.rc-monster.com/forum/showthread.php?t=4994
made my tray from some carbon fiber cloth scraps I had laying around ,depron foam and some good finishing epoxy...4 layers of 3.7 oz 80/20 cloth seems plenty thick .I made the bottom thicker with depron foam between the 2nd and 3rd layers so I could notch the bottom out for the mud guard nuts on my Cen MAtrix chassis. There are a couple pics here http://www.rc-monster.com/forum/showthread.php?t=4994
pinolelst
That turned out pretty good. You made the CF yourself?
"if you've got something to say, say it peacefully"
I use carbon fiber and glass fabrics to vacuum bag glider wings so I have a supply at hand usually .The depron foam is relatively high density stuff that has been used to form rc airplanes out of besides whatever commercial use it started out as and can be had in most craft stores I think in various thicknesses from 1- 6 mm or so.I just used some white EPS foam for the form and wrapped cling wrap around it before laying up the carbon fiber fabric .Then after the 4 layers and the depron bottom layer were all wetted out over the block I wrapped the whole mess tightly in cling wrap again trying to avoid any wrinkles that might show up and let it cure a couple hours before I trimmed it to basic size.
Really took me less than an hour to do and cost very little since I had scraps laying around and epoxy is still relatively cheap
hope this helps