Hmm, I guess I have a question, about projection specifically. I know at least that most magi stay away from using projection because it's impractical for the prana cost and the amount of time said projection can be maintained because of that, but is there anything more specific on those limits? I would imagine it to be more difficult to create something with more intricate parts, or something larger, but I'm not sure to what extent.
To approach my question from a different angle, about how long would someone of Rin's calibur be able to maintain a rubber ball, a sword, and a motorized vehicle respectively? I would imagine that that last one would probably kill her at least after a short period of time, but that's been contested recently, so having a lore master taking a look at it isn't a bad idea.
Don't know. But we do know that projection is not worthwhile enough that even master magi don't bother with it. Its function is mostly scamming the World during a ritual, by projecting a rare/non-existent ingredient.
Shirou's projections last long because UBW came with some hardcore structural analysis (the wireframe stove scene in Stay Night), so he can project things better even than master magi (who cannot perceive the minute details).
I would say Rin's rubber ball or swords are probably terrible compared to Shirou's. And she can't project a car, because the World will break it down faster than she can image it.
Also, did Extra Material do anything to clarify for sure whether the Nameless Hero/Extra's version of EMIYA is contracted to the Moon Cell instead of Alaya? I'm pretty sure that it's true, but I just want to be sure.
EXTRA EMIYA is not exactly EMIYA. He is not longer just "faceless Japanese Guardian NO. 103245356346", but a place-holder of all Guardians.