Zip ties at gun shows
All the gun shows I go to require them. Every gun in the place is supposed to have a tie on it. If you carry a gun in, it's tied at the door. If you carry a gun out, it better have a tie on it. Local LEO's are at the doors checking compliance. (Yeah, they may not be that effective, and a few get by anyway, I'm sure.)
You can't seriously examine a gun with that freaking tie on it. If you want to seriously fondle a gun, you have to ask that the tie be removed. Most dealers will comply, and have extra ties available. But some don't.
But most of them will if you provide a replacement for the one you're asking to be cut off. They're available at almost any hardware. I always carry a few with me. Anybody else?