3.75" is doable, but you'll have a slightly shorter crystal.
how much is slightly???
That depends on how much stuff goes into the chamber. Without accent washers, the crystal can be as long as 1.25." Without cap washers (on the ends,) it can be more like 1.5."
Ah ok... Well I assume I need the cap washers mainly to have the chamber stay IN the hilt....? I literally have less then 4 inches too work with and I would like the crystal to be as large as possible since the main focus IS the crystal in the hilt...
So with that being said what would you recommend?
p.s with your knowledge of what needs to light the leds up... is it possible to solder the crystal chamber up to my us 2.1 soundboard/AV switch so when I turn my blade on the chamber itself will turn on?
this is one thing that is kinda making me "Iffy" since I would hate to have to unscrew the hilt just to turn the chamber on kinda thing....
The cap washers are to provide some stability to the design; that way it doesn't twist. If it's going to be placed into the saber permanently, then cap washers aren't necessary. If it's going to be removed, well, then we're going to have some need of the cap washers.
And, no, you can't solder it to the soundboard; the LEDs are self-contained units.
The length of the chamber is dictated by the size of the crystal, but if you need it to be under four inches, the crystal cannot be more than 1.8" long, under any circumstances. That type of chamber has the crystal literally resting on the LED, and no accent washers or cap washers. All that remain are the structural washers, the LED housing, and the crystal, as well as primary and secondary posts, and the wire wrapping.