Colorado Mines could be a fit, particularly if she would like a beautiful outdoor environment in addition to a STEM focus. Under 5K students, many cool traditions, definitely a studious/“nerdy” vibe, and MechE is a particular strength. On the expensive side for out-of-state, but definitely a unique undergrad experience that seems like it might align with what your d is seeking.
Agreed that Rice, CWRU, Mudd, and WPI all sound like good possibilities as well.