[JThiessen]

So does your dad have any c-clamps or wood laying around in the garage? Go buy yourself a piece of 3/16 lexan, or Centra at the hobby shop. Measure your battery and mark the width lines on the piece of material (add 1/4" to your measurement - its easier to add material than it is to remove it in this case. Use a straight edge or a square to mark the lines.
Now, if you can, cut a piece of wood to match the width of your batteries. Clamp this onto your piece of plastic. Use a heat gun/hairdryer whatever to heat the material and bend it. Do one side at a time. Another thing - dont use too long of a piece of material and wood. Cut them to about 1" longer than needed in length to start with. Once you've heated it, pick up the whole thing and use the surface of the work bench or even the floor to make the bend. Keep in mind, you might have to try it a few times before you get the hang of it. If you end up using lexan, once it starts to bubble, you've heated it too much!