Reptile Brumation Methods

I found a thread from a couple of years ago on this subject, and I've certainly read a few methods and tried a couple as well, but I wanted to go a little more in-depth with it. Wondering what method you use for brumation (those that do it, that is), and how you achieve your goal. Be as specific as you can (how you insulate, control temps, etc etc...) Exterior structure means any structure without it's own temperature control (like a garage, closet inside a garage, shed....). I hope we can see some ingenius ideas!