Thanks for expanding a bit on the Optima design and manufacturing issues, bushmechanic.
Now, I'm wondering about the feasibility of sourcing components/plate materials and rebuilding existing and/or '1st generation' Optima cores to the same quality as the originals. Your thoughts?
Huh. I hadn't ever thought about "rebuilding" a battery. The materials aren't difficult to find, so that's not an issue.
The cells themselves wouldn't be a problem because you could take your time. Might have to rig up a spindle jig of some kind with a ram to get them tight enough, though.
The connectors would be easy.
The problem would be combining those two features in a limited home/shop environment. It's been done many ways, but I can't think of any that would be practical unless you just wanted a personal project. I certainly don't think a business could be made of it, but then again... Facebook exists.
Won't be easy, though. That said, it's always possible a plumber or pipe-fitter could chime in, call me an idiot, and show that I've overlooked the most obvious, five-minute way to do it.

My only regular interaction with lead is with a soldering iron.
Perhaps if I really sat down and thought about it I'd come up with a good solution, but I'm intoxicated enough at the moment that I find typing this sentence incredibly amusing.
Then comes the housing. If you want, you could keep the top as-is, but I don't think I'd be able to resist bolstering the connectors. There's no way around that being a pain in the ***, but it can be done in a number of ways on a workbench.
Hell, I don't know how far 3D printing has advanced. Might just be able to print a support to drop right in there if they're capable of using the right polymers.
Would it be a cool project? I believe so, but there are safety concerns, and it's not at all a weekend endeavor. This would be something to do purely because you desire to do it; perhaps even because you just like the look.
You could certainly build a great battery. Time would be on your side, and nothing beats that level of attention to detail. The design itself is solid, if a bit unnecessary. No drastic alterations would be required for improvement.
Might just be easier to pick up a new one and reuse as much as possible.
Regardless, I do encourage picking up a **** unit if you can do so for free or a few bucks just to pull it apart. You'll more easily see what I've been on about, and how it's possible for a design to be incredibly durable in use, yet equally vulnerable in manufacture. It'll be easier to understand the difficulties they encountered, as well.