Hi All
This mod was pretty simple to do, the hardest part was trying to avoid inhaling the blue-cap Crazy glue - man that stuff is toxic!
First the crystal:

Not exactly sure where it originally came from... I found it one day when I cleaned under the couch. I suspect the cats must have destroyed a Christmas ornament and that was one of the pieces they hid. It looks like a crystal, but it's just hard plastic.
Second is an UltraSabers blade plug:

This is the picture of the two things glued together:

I just used a tiny amount of glue at the edge and held the crystal on for a minute or two.
Here is the crystal chamber in the Manticore:

You can see the Manticore emitter is also sporting a couple of 1.25 inch O-rings.
Here is the lit saber:

I took a lot of pictures, but the light is so bright, you couldn't see the chamber in the pictures, so I finally went high shutter speed to be able to get this shot so you'd be able to see the lit crystal.