There is a glass concave piece inserted in the wood (link at bottom) and a small wood screw through the bottom into the glass piece for least amount of friction. I thought about scotch tape on the wood for friction at the top, but didn’t like the look. Sanding is a good point 
but maybe that is version 3.1 I don’t have 1/16" PG. I may have to get some. Great Idea! all the rest is draft board right now, as this was testing version.
Changing shape of blades? I may have to play with that. I’m not as worried about mass/weight with the small amount of friction of screw tip on glass, but every bit counts.
THANK YOU for the advise. Truly appreciate it.