Creating Chargable Effects?

So one of you guys has probably played Friazascape or Kohltastraphe's Realm. I was wondering a few things about how they made the effects. -Are the shapes created in a mesh editor? -How do you create a chargable effect with a part? Would it be something like if x key is held down, repeat growth of .2, .2, .2 or something like that? Thanks for the help, I'm just beginning scripting, I'd love extra tips.