If I remember rightly, it has been mentioned in either Thomas Kamps book or Kurt Schrekling's (SP?) book on Miniature Turbine engines and building your own
If I could find my copies of these I'd scan the pages and attach these here but they're buried somewhere in packing boxes.

I think it used 2 flat disks (One with a hole in it to let the air in). Sandwiched in between are curved vanes.