I have opted to mount the electronics in a frame constructed from Openbeam extrusions. The extrusions themselves are from Makershop here in NZ. The frame will consist of 7 facets fixed in a semicircular arrangement. Each facet will hold vertically 3 backpanels. This will provide a good view of everything and allow easy access to wiring.

TTN has printed that last of the brackets I need to put the frame together (thanks Jotham!). I designed the brackets with LibreCAD and OpenSCAD.

Shown in the photo are brackets for mounting 2 horizontal extrusions to a vertical one at 30 degrees, a 90 degree corner bracket and a bracket for butting a horizontal extrusion against a vertical one.