What happens if you take an octagon times an octagon times an octagon times an octagon? You get octagony! An octagon to the fourth power, if you prefer.

You need to print one "bracket" and eight "wedges". For the bracket I use 100% infill because it needs to be strong. The wedges will need some support because there's a part with quite a steep angle (67.5 degrees, to be precise).

The connectors don't hold as firmly as I was hoping, so be warned. Perhaps an intrepid user will figure out how to modify it.