Useful for shelves, wall decor, and so many other things! Check out this handout for more great ideas! Available in oak, walnut, and cherry woods. 
https://www.npcunlimited.com/uses-for-corner-brackets
 
Sizes vary depending on design, from 1 - 2 inches on a side. I can scale most patterns up (or down a little) to meet your need.
My default is 1/16 thick Oak, but can supply in Cherry or Walnut (1/16) or 1/8 thick MDF if desired.