Crossroads

I dont exactly know how to put the question im trying to ask but if one were to be interested in designing gadgets liek military science or something (my particular inpiration for this is advances in exokelaton and augmented reality research[example Land Warriors, BLEEX, etc]) what would one study and what steps would be taken to get projects started and researched?

What i think im trying to say is, how would i go about becoming a scientist who choosies his own projects and designs military or defense gadgets such as weapons and etc.

This may sound liek a childish or fatasy dream of what being a scietist is like but what would be the coolest thing in the world would be having a job like Morgan Freeman's character from Batman Begins where you get to create all kinds of neat stuff like combat equipment and vehicles and new materials and all that crazyt stuff >.<