Rack for outdoor battery box Projects

I have several electronics projects that run off a 12V lead acid battery (e.g. solar powered weather instruments). I was looking for an inexpensive place to store them. I found that Walmart sells a plastic marine battery box (http://www.walmart.com/ip/Snap-Top-Everstart-Marine-Battery-Box/16781380). It has a nice feature. It comes with a plastic divider so you can use different size batteries. The Cool thing is that if you are using a smaller size battery (e.g. Group 24), you have left-over "rac