I loved the idea of 3D Printing World's design of the expanding katana but soon realized it took 9 hours and 110 grams of filament, I was also scared that the sword would break and I would have to print is all again.
This expanding sword is printed in different parts and secured by a screw, this gives you the freedom to print it in multiple different colors and replace any broken parts, on top of that it only take 4 hours and 48 grams of filament to print.
Assembly: Just simple slot the tubes in from biggest to smallest.
Print it with the settings that normally best suit you, as it is not a detailed print I managed to push my Ender 3's print speed to 200mm/s. You may want to add a brim but I found it printed just fine without.