My first use for JB Weld was repairing brok marker light on a 1615 switcher. I found the replacements from Olsen's, and did some cutting, trial fits, and was quite successful with the repair. I have since added other repairs with restorations, of Junkers, and can't complain with results. It's great stuff, once you get used to working with it.
I am toying with an idea that will require using JB for construction of parts. It will be centered on a 1688 body, modified of course. Just rolling the idea around in my head. If I think I can accomplish my idea, I will have to get another 1688 body, to work with. Time will tell.