I was getting ready to do a mail-in and I noticed that it asked for a plain 3 x 5 paper. I've looked online and I haven't found anywhere that sells 3 x 5 papers, only cards. Does it really matter? There's nothing in the rules that explicitly prohibits them and my blank cards look exactly like white copy paper, you don't know it's a card unless you wave it around and feel the slight thickness of it. Are people sitting down, measuring, and cutting out 3 x 5 pieces of copy paper in situations like this or is it all really one in the same? I just want to make sure I don't get disqualified over something seemingly small.