do you decant the liquid and leave the yeast behind or do you just dump wort on top of the liquid as well as the yeast?I make starter in the carboy all the time. I make 12 gallon batches of lager and this is the only good method I have found. I start smaller in a 2 liter flask and then step up in the carboy.
I would think a large (inexpensive) stirplate could be made but I don't think the small rare earth magnets would work unless they make bigger ones. The stir bar is another problem too.This is an interesting topic. Soon we'll be seeing someone posting how they made a GIANT stirplate.