I applied through college or university. The process took 3 days. I interviewed at 3M (Ann Arbor, MI) in Oct 2014
Interview
3M was at the campus career fair and they offered me an interview when I spoke with a recruiter at the book. The interview was the next day. The interview was very relaxed and the recruiters were very friendly.
Interview questions [1]
Question 1
If you had unlimited resources, what would you make?
I applied through a recruiter. I interviewed at 3M in Nov 2013
Interview
Initial communication through a campus recruiter around late November, however, the contact was after the only round of campus interviews in early fall. I had a brief telephone interview over the phone and was quickly offered the position.
The R&D intern pool guarantees you a placement, but you don't actually get a job assignment until later ( Jan - Mar) when the hiring managers contact you to gauge your interest in the various intern positions.