Well... Since I demonstrated, somewhat obnoxiously, in Spat's thread that I was unaware SA welders don't have QR clips, I went and looked at the movie (extended version).
I dunno if this makes any difference. I'm just chucking it around to see what people think.
Hicks was of course the main source.
His dangles (fnar fnar) from the belt mostly. IIRC, someone said from being tied to him with a bit of string.
However, in the scene where he gives Ripley the Pulsemeter, he seemingly just slides it back onto his belt, suggesting some kind of clip like a bigger version of the ones on the side of a Minilite. Maybe he has a string loop that it clips to?
Then, when Burke runs from the firefight and locks the door, he just plucks it off his belt. Somewhere around this point, there's a shot of Hicks's left side and the welder looks to be clipped to one of his armour straps, under his arm but clearly higher than his belt.
Also, in the Extended Version there's a scene where Hudson picks up the hamster on his MT. As he and Vas locate the room, Hudson crosses between her and the camera. Just as he reaches the right side of the door, Vas's lamp shines briefly on his waist and you clearly see his welder.
It looks to me to be hung off his belt by a 1/2" wide strap, maybe like a 58 Webbing Yoke strap.
Based on that, I get the impression that the Welders have a clip on one side (maybe left).
In it's simplest form, I imagine it'd be something like this;
http://www.theclip.com/store/The-Original-Clip-p-16218.htmlHowever, if this does become something I do for my kit, I think Spat's clip would be more secure.