Hey, it's a living. Put out your hand, palm down, as we run through the DOF's. Oh come on, nobody's watching. Bases also vary widely in how far and how fast they can move, and in the angles to which they can tilt. Most are hydraulic powered - however, electric and pneumatic bases are starting to appear as well.
Several companies manufacture motion bases for the entertainment market.
Some are military contractors who needed a new source of income - Thomson CSF, Aura Systems, Moog, and Reflectone , for example. Another manufacturer, Intamin , builds roller-coasters as well as simulators. DDL , a new British company, recently patented a linear electric base. They all have their particular strengths and weaknesses. Part of my job is to play to the strengths of the base and steer clear of the weaknesses.