Yes Bob, I built my own prop balancer andI can give a 15 x 8 two blade prop a hand (finger) fast kick and it will take over 5 minutes to stop turning. Just an indication of low support friction.

I also built a CG locator with two metal knife edge support; one on each side of the fuselage.
I can find the verical line on which the CG is located with an accuracy that is the ability to read a ruler.
This locator has sufficient contact area to avoid damaging the structure and finish at the points of support.
I also sometime use the string loop method as a back up.

I enjoy this type of activity and it does not bother anyone else.

Zor