I threw together a battery hold down for my Optima the other day and took some decent step by steps. This batt is mounted behind my passenger seat, the hold down needs to be finished a bit more as its still rough, I wanted to get something done quick so I could put it in but its not bad for an hours worth of work. Once I am happy with it ill take it out and grind/sand/file some to get it looking a bit better.
About an hour actually, plasma cutters make things go alot quicker. I spent some time trying to figure out how to "skeletonize" the frame like I did but couldn't come up with a great idea so I did it freehand. That's the battery bracket with a quick coat of black. It's actually back about 15 feet, just a weird angle/pic.
I will probably be making a version 2, probably holes in the center instead of a skeleton. Truth be told I wasn't going for a maltese cross look just something that could grab all 4 sides so I will experiment a bit more before I settle on a design.