What material can I put along a sharp, thin metal edge?
I second Nate's comment that folding the edges is your best bet - it'll give you a small, slightly rounded edge, instead of a sharp edge, and it will stiffen your panel. The drawback is that you probably need a sheet-metal brake to make this happen in anything resembling a neat, time efficient fashion, especially for 200 copies.
This is a small portable brake, bigger counter top &amp; freestanding models are also available:
Image courtesy of HarborFreight.com. No endorsement implied. However, for your one-time use, this one may be right up your alley, so the endorsement is, basically, intended.
If, for whatever reason, you cannot get your hands on a small brake and can't find a local shop that'll do it for you, I'd suggest some clear rubber hose, something like refrigerator line. You can buy whatever diameter best suits your needs, then &quot;just&quot; run a slit down the length of the tube and slide your sheet metal in.
I say &quot;just&quot; because this will be time consuming, but it shouldn't be difficult. A sharp utility knife will easily cut the tubing to length, then will also allow you to slit it. It shouldn't matter too much if your cut wanders a bit (i.e. doesn't go straight down the length of the tube), as the tube itself will happily twist to line up the slit with the edge of the sheet metal.
The tubing is cheap enough that you can buy enough for a couple of trials to see if it will work for you, and you won't be out much if it doesn't.