I thought I'd respond to some of the questions raised in the comments, in a new post. I mean, instead of writing a comment myself and entering for my own giveaway, which is something I'm normally daft enough to do. But I was smart enough not to this time because I am finally getting enough sleep for my brain to work a bit! Ooo, I feel clever.
Some of you asked how the new strap would attach to the camera. I considered taking a picture of the strap on the camera but, well, I need the um.. camera to take the picture of the camera, so that idea went out the window. When I made the new straps, I used the black-and-yellow one the camera came with, as a model. The camera has a metal loop on each side for the black nylon straps to loop through. The fittings on the new straps are identical to the ones on the original strap, too.
So what I'm getting at is that if you have a camera that now has a strap like the black-and-yellow Nikon one I have, this new strap will fit it. When you've made yours (or won mine), just remove your old one completely from the camera and put this one in its place. You can throw the old one away or just reuse the parts to make another new fancy one.
And maybe the best thing to do if you want to make a strap, is to measure the one your camera now has, and copy it.
Good luck, all!
P.S. As of midnight tonight, the serger is still not cooperating. However, after fiddling more and oiling it and changing needles and rethreading and doing all the limited maintenance I know, it seems that it is the combination of the particular fabric and the rolled hem. So there is a reason! The serger sews beautiful rolled hems on other fabrics and also produced a very attractive overlock stitch on that weird fabric. Isn't it wonderful in an ironic way, when you figure out the problem and still cannot fix it but are so foolishly joyous? It is pitiful how low my expectations for happiness are sometimes.
Edited to add an update: I've had a request for the pattern for the black vinyl piece from a commentor who hadn't a camera strap to copy, so I've added that in the original post. It seemed a waste to scan and post a whole sheet of paper for just a tiny little image, so I added my usual nonsense and made a cheat sheet/summary for you all. Plus a quick sketch of how the camera strap attaches to the camera. The drawing is a bit wonky since I just dashed it off to fill space, but hopefully you'll get the idea.