Update: I am quarantining some tangs to add to my tank so I actually bought a commercial magnetic algae clip to use in the QT. It's certainly nicer than getting my arm wet, but I still like the one I DIY-ed for a couple of reasons.
I've found that my fish like it more when the clip is facing up as opposed to down, and on the commercial algae clip, there is just one magnet used and the clip isn't rigidly attached to the magnet, so what it means is that the clip really likes to face down. I was able to hot-glue it so that it could stay up when I wasn't moving the magnet, but it is a little more of a pain to load the algae on it. Also, it doesn't slide along the glass nearly as well as the magnet-cleaner does, but that can be fixed with a small piece of cloth in between the outside magnet at the glass.
I thought I'd want to use the commercial magnetic algae clip in my display tank after this QT finishes, and just use the magnet cleaner for cleaning purposes, but after a couple of weeks using it, I think I'm going to continue to use my DIY magnetic algae clip.