My wife purchased an LED Christmas tree with these little white balls covering the LED's on the end of the twigs.
They drop off and easily get lost.
I whipped out the callipers and knocked up a replacement in TinkerCAD.

Creality

Ender 3

No

No

0.12

100%

I used a glow in the dark filament which easily lets some light through to match the original material as close as possible.
To make sure it was as solid it was printed with 5 walls and 100% infill