This is a VERY Strong 90 degree corner bracket. Necessity is the mother of invention… or so they say… Anyway I was installing a very large mailbox, and needed a way to reenforce a 90 degree cantilever arm meant to support a normal sized mailbox. So I went inside, made some lunch, sat down at the table with my MacBook Pro, and 300 healthy calories later, I came up with this bracket. I printed it with 6 walls, and 30% Cubic infill, and boy is it ever rigid. Complete overkill for most needs, but it fixed my problem of a wobbly mailbox post, that's for sure. 

Maybe it can fix something of yours, too. Happy Printing.