I made this bracket to keep my batteries in a line. It's not intended to be strong. there are stronger ones. The idea is to make them wobble less. The wall is supposed to be 1mm, but for some reason it is less than that. I could increase that if I get requests to do so.

I printed with PLA and 30% infill - turned out 10.14g. It's probably not a good idea if you intend to draw lots of current and the batteries get hot. In theory you should not allow more than 50 deg. C but I would suggest at least PETG. 

The + and - signs can be printed in red/black and glued to the main print using CA glue. Now the problem comes when you use PETG - it's a bit harder to glue. So try to sand both surfaces before gluing. Or you can use a marker to mark polarity - also works.

I printed also with PETG. Gluing the + and - is not as hard as expected. Just clean with alcohol and hold steady or use accelerator.

Update: Added a model with mounting tabs. Hole diameter 5mm. Intended for 4.5 or 5mm wood screws or M5 machine screw