USB Box mod question. What can I use on it?

[BJ43]

Well.......I said I would not upload a photo, but I had to. Forgive the crude design but it is my first mod. I kind of went for function over fashion on this one, but future ones will be improved.
I am running this on a 5V 4A wall unit so the vapor volume and heat are really good on dual cart. This will save me burning through my small ego batts sitting at home in the recliner.
Thanks for all the help Java_Az.

Great, I use PT's 99% of the time, from my first made from a tire stem in 2008. I did learn one thing for me, I put the plug on the side now so I can stand the unit upright. Many attys and tanks leak if horizontal.