New HUB-15 part will be added to the site today. 
I wanted to make it easy to mount a bracket to bracket at a 45° angle. It can also be used as a simple 1/4" spacer. We are also getting a 1" version made. Here is an image of the new HUB-15’s.
Fantastic! I’m not sure what you mean by bracket to bracket at a 45° angle. Got a photo example of this?
EDIT
Never mind, I understand you meant by clocking the various screw holes to get 45°
Yeah, that’s the ticket! 8)