I've done tons of googling and research and it looks like a lot of people claim that the purple puzzle swap pieces are gotten through spotpass. My 3ds is always in sleep mode unless I'm playing it, and I've never gotten a spotpass puzzle piece. So I'm wondering if that's truly how you get them. I haven't even gotten any pieces from my hours and hours of mario kart 7 online play. Also, I don't live in a very populated area so a streetpass is rare. Even at my college, I only get 1 streetpass if I'm lucky. Usually that streetpass is from this kid who somehow has every puzzle completed. So is my best bet just to take his purple puzzle pieces when I streetpass him? Because that seems to be the only way to get them. I have about 2000 people in my mii plaza (all but 10 are from online gaming) and the only purple pieces i've gotten were from streetpass. So I guess my point is that if you truly get purple pieces through streetpass, then how?