This instructable will walk you through how to make your own angle corner brackets out of steel. They're great for building or strengthening shelves and table tops; handy if you need something custom; and anyway much cooler (and more available) than the stuff you have to rifle through at the hardware store.
I made these brackets from my own scrap material using the tools at Techshop Detroit (www.techshop.ws
P.S. I made these brackets using safe, one-off, garage-shop style procedures. Incorporating jigs, fine-tuned fixtures, and calibrated materials would increase accuracy and efficiency for production. RULE OF THUMB: "Making more than 3? Make a jig for it!"
P.P.S. This is a great example: Drill press repeat drill fence fixture