So, I have seen things like this and had to see if I could make it simpler yet effective. I bought an inexpensive metal hood, 10 ft. of solid core fiber optic cable, a knock-off diffuser for my Metz flash and some matte black paint & crazy glue - overall about $30 in parts and about 2 hours of creative labor - and while crude, I am pleased with the results!
The process was as follows:
* Screw the hood on the lens and mark the top with a sharpie, then unmount it from the lens. Helps when deciding on lengths of cable later.
* Drill Eight 1/4" holes in the hood - best to do a pilot hole first, but pretty straightforward.
* Drill Eight 1/4" holes in the front of the diffuser, then paint it black inside and out. I did this to eliminate stray light - I wanted all the light coming from the fiber optic cables.
* Cut the cable in lengths to allow them to be mounted around the perimeter of the hood. I also cut the end near the hood at an angle to allow it so the light was focused away from the lens itself.
* Mount the cables to the hood with crazy glue, then mount it into the diffuser the same way. I used some cable-ties to group the cables into two bundles.
Then you screw the hood onto the lens and put the diffuser on the flash!
The good: It works! For mine I need to have the flash level maxed out, so I know there is still some work to do, but doing that has made this much more useful than a cheap ringlight (e.g. Poloroid, etc.).
The changes: I know I will be building another one soon. This one works fine, but what I will change is that I will use stranded instead of solid core. I still want to use jacketed cable since it is easier to use, but the stranded has more flexibility which makes it easier overall and more compact. Also, I have found a vented hood where the vent holes are on the rear of the hood and slightly angled in front of the lens. This will allow the cables to come in from the rear of the hood rather than the top, so when you set the camera down it is not pushing on the bottom cable.
But if you enjoy macro but are hesitant to spend the money on a Pentax or Metz ringlight, this is really worth playing with! And it gives you some nice satisfaction to see results you didn't expect.