I'll take some proper shots of the setup soon.
I will probably also make another one, but I will install a relay or something else to only allow a very quick flash, I will explain the fault and design decisions with the current one.
So, it's a ringlight, not a ringflash. It is triggered by the hotshoe and uses two 9V batteries connected in series, it is quite bright but will mostly be used for catchlights in portraits and for a little fill when I shoot live bands.
The downside compared to a regular flash, is as soon as the M9 opens the flash circuit, it stays open, so I have installed another switch on the battery housing so I can power cycle the circuit and have the M9 shoe 'reset' as it were. If any electronics gurus can tell me the part I need to basically make the circuit shut off within say 1/50s after being opened I would be all ears.
I originally put it on a step-up ring but it obscured too much finder space so I got a tiny quick release clamp and attached it to that, so now it is suspended just in front of the body around the lens mount, makes changing lenses difficult but leaves the finder very open and unobscured.
All in all a fun exercise and a pleasant result. Please excuse the white balance and my obviously dirty mirror.