Today the ring flash adaptor I ordered from eBay had arrived. It looks something like this:
Construction is solid but unfortunately, the light distribution is something much need improvement on. The section closer to the flash source is brighter and it darkens down quickly moving away from the flash source. I've modified it a bit by taping some paper on the brighter section to dim it down a stop or two.
Here's a self portrait taken using this adaptor:
I want to use it during evening wedding shoots, but need some more experiments first.