E6000 is an industrial-strength glue made from a clear drying, flexible epoxy that works well on wood, metal, glass, ceramics, rubber, vinyl, leather and (most) plastic. It dries very clear, though can form air bubbles if you're trying to use it as a sealant. It can be hard to get the exact perfect amount of glue, and can goop out the side a little if you're trying to glue back together a broken vase.
However, it rubs off like rubber cement until it's dry. It takes about 30 minutes to an hour to make two items stick together, and at least a full 24 hours for the bond to really set in. It's biggest strength is its strength, even when trying to glue metal to metal. If used properly, it's very unlikely a human will be able to pry the two pieces apart anytime in the next few years. Its weaknesses are styrofoam and gluing things that aren't laying flat —it takes so long to dry that gravity will move things around before the bond sets in.