I used the 55mm ball without any coating.
There is a small injection defect on the “poles” of the ball that is visible from the insight only, so when opening the hole orient the ball so it is opposite to the nice flat area.
The last part of this post shows some variations of the light.
And all the measurements of the LED drivers in this post are also using the 55mm ball.
I would recommend blocking the back to avoid external light to blend with the surface of the ball.
Was also considering experimenting with painting the inside of one, but put it aside for now.
Is it good enough… yes, very much so. No 3D printer here, so I try to use what is available.