There are a bit of things in my studio that I can't live without. If I had to choose a few items right here, right now; the first would be my copy of Complete Metalsmith because I refer to it from time to time. Second would be my copy of Creative Metal Forming; such fantastic book! Inspirational photos and projects to help you learn. Third would be my copy of 1000 Rings; it has been my favorite book in my studio for many years! Forth, is my rawhide mallet and my dapping block; my work, right now, consists of a lot of domed circles and these tools help make them. And fifth; is my Optivisor; I quite quite a bit of fine detailing and these help me see tiny things, without eyestrain.
If interested in more things that "I can't live without"; I wrote a post on jewelry books reading a while back; you can read about them here!