Whatever happened to good-old two-part JB Weld? Is that just a regional product? I thought everyone knew about it.
Sugru is a putty. It's squishy, kind of like clay, and air-cures to a sort of rubbery flexible solid. It's good for repairs to things that are flexible (It's great for repairing and ending stain relief to cables) and also for adding "bumpers" to things or even molding small objects (like hooks). It's also safe to touch uncured Sugru with your bare hands. This makes it a lot easier to work with, in general.
The big downside to Sugru is that it's expensive, it goes bad after a few months (but storing it in the fridge extends the lifetime to a couple of years), and once you open a packet, the whole packet will cure within 24 hours. You pretty much always end up with some waste. If they could somehow make it 2-part so you could make the exact amount you need, or store it in a tube or something so it wouldn't go bad so easily, it would be great.
When the JB Weld putties you're talking about cure are they hard and brittle, or flexible and squishy? The ones I'd used all cured to a hard plastic.
Still, that's an epoxy, and if it's like the epoxy putties I've used, I bet it cures to a hard and rigid plastic, rather than the soft and flexible rubber that "Sugru brand mouldable glue" cures into.