@Blackrat: I've got some old bars and pieces of lying around, got these stoppers from that pile.
As for use cases, pro's and con's, I haven't thought it through. Was messing around in the workshop and came up with this literally earlier this evening. Seemed pretty cool to me so I thought I'd just put it out there...
And yeah I do have some application in mind but will wait until I've done some real world testing before recommending anything.
For now, it's easy enough for anyone to try and see for themselves.. in fact, I would like to see pictures of your own versions of this, with double or triple hitches