I use a regular nori clip attached to an acrylic bracket that I fashioned with a heat gun. The bracket hangs on the rim of the tank fairly close to my autofeeder. I tried the elastic scenario on a piece of live rock and didn't really like the way that worked. I also read about the pvc method but that seemed like too much hassle as well with the elastic issues as you've experienced. Inevitably I didn't do a good job of wrapping the elastic and tang man would tear it right off it's mooring. The clip has its cons, but at least it secures the nori fairly well. I soak the nori just a little and fold it in half before putting it in the clip with just a little protruding. This means every so often I need to pull the clip out and expose a little more nori, but with the bracket set up that's fairly easy and very little gets wasted that way.
I experimented with chopping up dry nori and putting it in the auto feeder with the flakes & pellets, but that didn't work all that well. Seems the bits of nori floating around with the flakes somehow didn't spark the interest with the two fish that regularly take nori. My yellow tang & singapore angel are just too accustomed to taking it from the clip now and mostly ignored the nori that floated with the flake food. Might still do this if I'm away for a few days. The tang will go after the last remnant of nori from the clip when I release that into the water, but usually there aren't a bunch of flakes floating around to distract him when I do this.
Here's the bracket with clips. I only use a single clip since I don't have that many veggie eaters in my system. All you need is a heat gun or torch, scrap acrylic and a nylon screw. I tapped the acrylic so the screw threads right in. The screw head holds the clip quite loosely so it dangles to and fro, like real algae in the ocean. The tang & angel seem to enjoy making it bounce when they tear away at it.
