You can buy one (2 playcoins each) or you can get them by doing streetpass with people (1 piece from each person)
To get a new panel you have to meet with someone over StreetPass and then you can choose one of their pieces of any panel they have. Sometimes, especailly when new panels are released, you can get new pieces via SpotPass and special Miis
You can either get them via SpotPass or get them from your friends with them. But you can't get them with Play Coins.
Mii Plaza is for Streetpass content. When you pass by another person with a 3DS, the two systems will exchange data, and their Miis will show up at the plaza. Each Mii can be used to play the Mii plaza games, 'Puzzle Swap' is the default game, though more can be purchased.
you simply have 2 3DS's. you can use them to make a streetpass every day that will help you with the mii quest and/or the puzzle swap!
The number keeps growing but tag a special mii and I'm pretty sure that that's the full total (so far)
Puzzle 26, Train Swap, Location: Broken Train. Please see Related link below for a walkthrough of puzzle 26.
Pal Park.
Puzzle No 26: Train Swap, Location: Broken Train You get a Hamster toy for solving this puzzle Please see the related link below for a walkthrough of this puzzle.
swap your old ds in game and you will get some money taken of the orgianal price When can i swap my old one in and how much will get taken off ?
Puzzle No 119: Swap to Unlock. Find three hint coins, Tap on the doors of the Layton's car. Please see the related link below for a walkthrough of this puzzle.
so you can swap stars for points
Under the scuttle panel. Remove wipers then the panel, it's held in by elastic band so easy to swap