From the game.pdf:
Rule S4. The Students and Mentors must remain in the Alliance station during the match. They may not reach over the playing field.
I found nothing specifing aluminum or plexiglass as the boundary.
I personaly would judge it as breaking the plane of the font side of the barrier, be it Alum or Plexi.
But I am not a judge or referee, so ignore my imterpretaion.
