Nope, a great, big oopsie on the guard location, didn't leave room for the string to engage so I made another. The string release mechanism has rounded edges and is polished now so no chance of it damaging the string. The limb is a blank fibreglass bow limb I bought on ebay for $7, only short at 500mm but it has plenty of oomph. The weed eater string will more than likely break, as you say, with use but, I can't imagine me ever using it aside from trying it out to be honest. It was just one of those things I've always wanted to make. Next project, a rifle slingshot. Again no use for it but one of those things I've always wanted to build. That's one good thing about being old and retired, I have the time to make all manner of useless things. Nothing else Good about getting old though, it sucks. Painted it today and polished the alloy, should make a nice, wall ornament in my workshop.