Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:2841384.

i made this with using a simple battery and led to light baby groot up. there are 2 holes in the battery holder for the led leads to go into to make contact with the battery. the battery and its holder stay outside but led goes inside groot. i bent the wires of the led so the led bulb goes upward into groots insides. i made mine with clear pla but white might be better or any other color would look nice. 0% infill, no supports except on the battery holder. i use 3 in and out and top shells, tho i dont know if this makes a difference.

watch it work: https://youtu.be/sIRmeB926NA