extrusion/tube corner connector

Connect like sized square tubes or aluminum extrusions and connect them together to form the corner of a box shape. This design is fairly customizable.

It might take a few iterations to get the hole size a good fit without being too loose. The good news is you can change that hole size without changing the outer size so the parts will still all match.

SLICING NOTE: I noticed that Cura would try to bridge the length of the one shaft and the width of the other shaft, so I turn the part 45 degrees to the side when I slice the part. This may not be of importance if you actually print with support material though.