[MrForbes]

As far as I know, you are not likely to find any angle brackets ready made to that specific size and hole layout. Usually when designing a mechanism, you either plan on how to make all the parts before you finalize the design, or you design around parts that you can buy.

There are some tricks to making parts with holes in the same place, you can make a drilling jig that supports the part in place, and has a hole for each hole you need to drill, that lets you just put the drill in and it automatically aligns it. You would (edit: might) want to drill the holes before bending the part, too.

It need not be fancy, just needs to do the job. Look around and see what you might make it out of.