This is nothing fancy, only a use idea for the humble prim cube set to no copy:
You know when you're working on say a few dresses with a texture hud, and you have to stop before you finish. You take it up into your inventory. Next time, you rezz a copy, but the unfinished copy stays in your inventory. You have to stop again, and now, you're completely confused which version it was you were last working on.
This copy stopper will allow you to store your project without making multiple copies of it into it (unless you deliberately make it so.)
(First, take a backup copy of your unfinished items as normal if you're worried.)
Rezz the copy stopper, and rename it as something that makes sense. Pick everything up as soft link set, with the renamed no-copy prim as the root. The next time you rezz it, it will take it out of your inventory onto the ground, rather than copying it. (NOTE, however, that rezzing no copy items is always a bit risky, so make sure you've got enough space for it, and keeping a messy backup somewhere is still a good idea.)
This pack contains 50 objects, buy a new pack if you run out. They're completely reusable of course, and also transferrable if you need to pass them to a collaborator.