I know I've read a bunch of little tweaks to the crafting and modding rules for lightsabers, but dang if I remember where they all were. I found "add Force dice" in the CRB, but I'm pretty sure there's also "may use Lore instead of Mechanics" and "reduce the difficulty for your own lightsaber" somewhere. Of course there's "free 1st mod" in the GM kit, and I think something in Keeping the Peace? Someone has to be keeping track of all this.

There's actually a full description for building a lightsaber hilt and the difficulty in the GM kit, but my books aren't accessible right now

GM kit pamphlet has the full rules for lightsaber building.