Machined AL battery trays

[TexasSP]

You can get C-Channel 6061 which would do the trick. Just pick the closest size you need, machine out the excess then add to end pieces the use screws to hold them. Weight could be just as light as delrin and some other plastics.

I bought some C-Channel aluminum about 2 years ago at my former employer which we used on machine we were prototyping at the time. It saved a lot of waste both in material and time.