I recently designed a new battery cart for my team. I designed it to be able to fit and charge 9 batteries at once. (I plan on widening the battery compartments by an inch. Too tight of a fit right now). If you look closely though, you'll see that the aluminum actually has a slot on the ends. I plan to put some sort of material in between the slots but I don't know what material to place. Any suggestions will be most welcome. Also, I designed it to be a bench for my team so on the top there'll be some sort of covering BUT I want that to be a hinge so then underneath I can place chargers for power tools and such. Lastly, if you look in the front, you'll see two different colored panels - this is how I plan to access the batteries. The top portion will be rigid while the bottom will be hinged so if we need to access batteries, we open the bottom one down. When closed, it will be latched with the top. Obviously, though still need material suggestions for these panels too. The only issue I see is that the cart may not be able to support the weight of batteries, chargers, and humans. What you guys think of that?