Well, so would a custom mood, assuming that's even possible.
And Jedi ought to be rare. In a galaxy of billions of sentients, the Jedi Order had a small enough population that its highest echelon was, what, twenty guys?
Force sensitives wouldn't be impossibly rare (probably one in a hundred humans, less for species that are rarely force sensitive like Hutts, more for species that are frequently Force Sensitive like... whatever Yoda is or Kel Dor) but rare enough that finding one would be a boon. We could probably add a small indicator, and perhaps have a way to artificially trigger the Jedi/Sith abilities... Perhaps, like you said, a 'create lightsaber' reaction in a custom shop that also creates a small bit of gas that triggers the force powers but requires a rare crystal (with the various focusing crystals being reagents for different colors of lightsaber - Adegans make blue or green and are the most common, Synthetics can be made by consuming multiple lesser gems and always make red, and rarer crystals that exist at like, diamond rarity could pop up in Adegan clusters, allowing you to get rarer and more valuable colors like orange or purple)
I don't think there's a way to make it so only Force Sensitives can make lightsabers, but they at least would have a greater rate of learning with them - if we attach it to an unused skill, we can lower that skill rate for other castes, reflecting the idea that lightsabers are clumsy for those not skilled in the force. On the other hand, if we attach it to concentration, lightsabers are a great training weapon... huh, perhaps we could include a 'make training lightsaber' reaction, where training lightsabers are considerably weaker but somewhat easier to produce (you can use any lesser gem to pump out a simple training lightsaber). It wouldn't trigger Force Sensitives into full blown Sith/Jedi, but would allow you to train Concentration, which would theoretically make your soldiers better students as they master the intricate forms of lightsaber combat.