I checked a pocket knife in Europe when it was unexpectedly found in a backpack pocket. They put it in a padded envelope and checked it. And it came out the other side.

Also not really small, but I purchased a boomerang behind security in SYD and carried it on the plane to LAX only to be told by security there that I had a weapon. I'd be more dangerous throwing my laptop at someone than a boomerang, but I went back to the counter and they stapled it into a paper bag. I was sure it'd get broken when someone threw a big bag on it, but it also arrived just fine.