This is a simple remix of the retractable lightsaber with a direct fit flashlight.  The flashlight can be bought from Harbor Freight at $2.50 for 2.  Overall length of the hilt increases by about 80 mm.  The ON/OFF push button is at the bottom of the hilt

Printed in translucent PETG with 0.2mm layers.  The flashlight is press fit into the cap end of the hilt.  The flashlight does vary dimensionally +/- .25 mm so some fit a bit tighter than others.