For years, when people asked me "what kind of bondage" I like my response was always "tight, taught, or tough;" the closer to complete immobilization the better. As control has been becoming a bigger thing for me, metal has been becoming a HUGE interest. I'd discounted it for years because under most circumstances it isn't that overwhelmingly restrictive, but when you're in a situation you want out of it's often more effective than rope or leather. Unless you've got the keys or tools? Yeah, you're FUCKED. After a decade of chasing after the most intense bondage I could find, all of the sudden the idea of having my hands handcuffed behind my back and a chain padlocked around my neck by an aggressive guy gets me as hard as an intricate shibari-style tie does.
The moral of the story: it's important to revisit old ideas when you feel your priorities beginning to shift, or even just on a regular basis. Now that there are things like Tumbler it's a lot easier to do since you can subscribe to people who have similar interests that might pull in unexpected things.