This is a begleri bead that has space for a small battery and an LED.

Battery Type: 3V CR1025
LED Type: 5mm Straw Hat LED Multicolor Fast Flash (the exact model is this one on amazon https://www.amazon.com/Multicolor-Flashing-Changing-Electronics-Components/dp/B01C19ENIW)

Assembly Video:

Print settings: 
Infil: 30%
Supports: On build plate only