Wall
They are Steel ball bearings except the 1 small one in the entry that is a "water" marble, you can see how that one refracted the light inverse of the others.
Thanks Elfishone, I put a photo of the set-up in my gallery if you're interested.
I am ;new to GPR. I loved your gallery. You are very creative and offer much inspiration. Congratulations on being in the spotlight.



Thank you....just lucky!