This sounds like an interesting concept. The possibilities for a tulpa is vast, and although it seems impossible, if it is possible I'l start reading on it on Saturday, since tomorrow and Friday I won't be able to.
Question, will this be hard if I can't lucid dream? I've tried memonic and MILD methods but they don't work, and I always fall asleep before a WILD dream can occur. Although my dreams have been (rarely) becoming "semi" lucid recently. I am concious during the dreams and can make decisions that affect the dream (although it's hard to do), but I don't realize it's a dream. And during tests will the tulpa be able to help me, or will it just hinder me (since I'm starting college soon, this interests me).
And to visualize a 3D Rainbow Dash (since I have a hard time with visualizing MLP ponies in 3D, especially the face), should I make a folder and gather all my 3D rainbow dash images in there to help me?
-EDIT- Also, can you have 2 or more tulpas at once, and/or modify the tulpas appearance without banishing and remaking one? And if you try to banish one, will it protest?