This is definitely not a 12X scale modular Lego Lightsaber seen here: https://www.youtube.com/watch?v=QxVBF9aY2yo (the one in this video was a previous version that needed glue)
The parts are assembled without glue or hardware. All you will need is a mug of hot water (I'll explain).

The Hilt is made of 4 parts that all screw together and take 9h45 to print.
The Blade is printed in 2 parts, in vase mode with each half taking about 1 hour.

All parts are saved in the correct orientation for printing and are to be printed without supports (except for the bottom of the hilt).

Hilt build instructions:

Print Hilt Top 1x
Print Hilt Middle 2x
Print Hild Bottom 1x
Screw all the parts together
Note: If the screw thread tolerances are too tight, simply dip each of the male ends of the screws into boiling water for 3 to 4 seconds and then try to screw them in for a perfect fit.

Blade build instructions:
Print Half Blade Twice in vase mode with 3 bottom layers and no top layers.
Then, take one of the halves, hold it vertically and dip 5-6mm of the open end into boiling water for 1-2 seconds. This will cause that end to shrink, allowing it to press fit nicely into the other half of the blade. Glue is optional but not required to hold both halves if the blade together.

If you wish to remix this here are some key dimensions:

The OD of the Blade is 35.6mm. The ID of the hole it fits into is 36mm
The screw threads use these parameters in fusion 360:

Thread: ISO Metric profile
Size: 30mm
Designation: M30x3.5
The male threads stick out 12mm