Under the current rules, a Force user that wants to modify the crystal attachment in their lightsaber has to use Mechanics the same as they would to modify a regular attachment.
I propose that Force user be allowed to substitute Discipline for Mechanics when rolling to modify a lightsaber crystal attachment. It plays into a Jedi's construction of a lightsaber being less about mechanical ability and more of a spiritual thing, attuning the crystal so that the lightsaber becomes less a weapon and more an extension of the Jedi's self.
As a possible addition, when it comes to modifying a lightsaber crystal, allow the Force user to add one boost die per rank of Force Rating they possess; so a PC with Force Rating 2 would add two boost dice to their Discipline pool when trying to modify their lightsaber's crystal, but said boost dice wouldn't apply if they were trying to modify an Extended Hilt attachment, which would be a Mechanics check.
Edit: The intent of the above was that It should be that only the person that's doing the modification can use Discipline to modify a lightsaber crystal; you can't hand your 'saber off to another PC and let them use their superior Discipline. This might be too much bother to track for this system though.
Edited by Donovan Morningfire