The Linking Safety Pins has been one of my favorite tricks for years. One of things that I do are two phases where the pins are totally out of my hands and someone from the audience links or unlinks them. However my favorite part is the final unlink where I pull the pin through the pin that they are holding.
What draws me to this trick is the simplicity of it. It uses two large safety pins. Everyone knows what they are, they can be examined before and after the trick. Also they take up virtually no space in my pocket.
The downside is that the good oversized linking pins haven’t been made for a long time, so they have to be found on the used magic market. There were soo many sold, they frequently pop up and I’m always buying them whenever I find them. If you’ve never done the linking pins, the trick Shrapnel which is currently available is a good routine and it uses more standard size safety pins and worth looking into.