I have meant to post a howto for a long time now, but always it gets put off.
Here are the files:
Here is a link to the files I used for ChubbyIII(DTP). I widened the chassis and the shell. To make this work for 2.8 or any version, you will need to widen the chassis. 12mm is the extra I added IIRC. The extra space allows you to have 1/2" (12.5 mm) endcaps fit.
For the thicker endcaps, I used a drill press to drill holes into the side and again down from one side to push the wires through for potting.
The battery tubes are also thicker. I used 1/8". The batter tube endcaps are also thicker. I am not sure they need to be, but they are small and you can often cut them from scrap 1/4" any way.
This is a picture of the potting holes drilled into the side of the endcap. Doing it this way allows you to save space and still have a strong solid 1/2" endcap. Hooray!
I just typed this up quickly and so obviously I have a lot of gaps to fill. If you have questions, please ask them.