There are a few sites that I've had success pulling from, but I've never been a big fan of cross posting sites and then having someone run into a horrible experience (I pointed someone to a website that unbeknownst to me, had recently been compromised, and caused all sorts of fun. Still felt bad for pointing anyone there, even though there was no way I could have known)

That said, I found a couple different safety hooks, not sure which design you're looking for... more of a hook with a folded sheet metal tab, or more of a caribiner profile?

My apoloies if you've already checked these, I am guessing you've done a much more in-depth search than me, but on the off chance that gogle was misbehaving, oddball search limitations from your ISP, etc...

Biners would be the easiest, those even show up on Thingi....

When I checked for "safety hook 3d" a number came up, different designs... trace and turbo I believe I've used before for various downloads, some of the other sites are a bit more finicky, or have you upload 20 before they let you download one, etc. Depending on which style you're looking for, I might have something from an old catalog CD that I got from somewhere... (I don't remember where it's from, I'd have to look... a bunch of off the wall items on there as well.)