The Main difference between this thread and the main Mechanics thread is this will discuss more character building items like Feats/Merits from the legitimate Dice rolling and math.
So I'v brought mention to the Class system as a style where you can quickly grow in one class's section and grab a few skills from the other classes at more cost. So I'm thinking of a Buy In system with this idea. You character has done something so he could do these things fluff wise.
For example lets say the Buy in on the Manipulator's skills is a small generator that been modified. So think what a university professor would have in the intro labs that been modded to do field generator's work up to a degree. So it would cost your character some much XP, Credit, and possibly some skill manipulation. Add some to Sciency skills but lose some of your melee combat due to the minor radiation sickness you acquired from using it.
Not only would you be limited to a point but it would cost more to do so but having an Operator strengthen or make his drones more faster by manipulating the metals could be a neat trick. Or a Saboteur that creates a flash bang from nothing.