Tealight candle holder. Use only battery powered as not tested with naked flame and likely to melt and cause a fire hazard.
If you're using a transparent / semi transparent filament that the light can pass through easily just put the tealight at the bottom for an ambient glow.
If you're using an opaque filament similar to the one shown, print the inner which will allow the tealight to sit higher so the light is visible out of the top.