where can i get some so i can make my own oval battery tray?

hmmmm well It may not be the cheapest way to get it but i would check out tower hobbies I believe brp sells some for a reasonable price. but if I were u. just hunt around till u find the right one cuz I bet u can get it for alot cheaper than you can make it. just my $0.02

where can i get some so i can make my own oval battery tray?

I've used some from this company, with good result. Available in various thickness and finishes.

http://www.acp-composites.com/

you also can go to www.penguinrc.com, they have all different sizes and thickneses you can buy