3D Corner Bracket

Hi!

I'm trying to make a aluminium box out of 6 machined (with an AXYZ 4008) metal sheets. I do not have access to bending, so I'm looking for some corner brackets to create the corners of my box and join the 6 sides together.

Does anybody knows if this kind of part has a common name? Does it exist stock or do I need to have it machined?

I've included a pic of the current design of the box in SolidWorks. If you ask, the box is a matrix of 5x5 MR16 Lamps for a show lighting effect.

This is the MISUMI part I've found to be the closest to what I need : http://us.misumi-ec.com/us/ItemDetail/10302061170.html

It would need to have the 3 holes threaded with 6/32, 8/32 or M4 or M5.

Thanks!