Okay listen
You don't need a padfolio for a medical school interview. Wanna know why?
1) The primary purpose of a padfolio is to take notes or to hold copies of your CV. You don't need to do either of these things.
2) Your interviewer will either know nothing about you (MMI/closed file interview) and will want it to stay that way or will have access to your file and will know it as well as you do. Thus, you don't need your CV.
3) There will be nothing to take notes on. You want to absorb the feel and atmosphere of the school by listening an observing. There's nothing to take notes on. You need to give yourself time to form an impression. The proper time to make notes about the interview day is once you get back to your hotel after it's done, and then revise them after a night's sleep once the "WOW" factor wears off. You should not be taking notes during the interview day. Everything you absolutely need to know will be given to you with your interview folder/packet, including financial aid information. All you'll accomplish is looking like a tool.
4) If financial aid information is really important and the printed information they give you for whatever reason won't suffice, write on the back of the sheet that they give you. They rarely print double sided.
5) That being said, none of this information matters until you're accepted. If you are accepted and you need information about x,y,z call their admissions office at that point and start asking questions. They will be
very happy to answer questions or refer you to people (such as the FA office) who can. Until you get in though, there's no need to compile information about every single detail only to have none of it matter when you get rejected.
6) Just an anecdote, but for one of my MMI interviews, on the 3rd or 4th station, I went into the room and the interviewer told me "oh thank god you're the first person to come in here without a damn notebook and a bunch of scribbles on it" which leads me to believe that it was looked down upon (and also you should be spending your time thinking during your 2 minute pre-MMI station planning time and if you can't remember something that you have literally only 2 minutes to think about then I can't help you)
7) Taking notes during an interview doesn't make you look interested. Just foolish. They already know you're interested because you're sitting there in front of them.
tl;dr I agree with
@gyngyn
Just bring a pen with you.