This series of DIY images allows you to create your own portal mirrors. Just remember that they're made of glass before you are tempted to jump through to another dimension -- because the only place glass will transport you is to is the hospital.
The mirrors mimic the cult game 'Portal,' which involves creating other dimensions in order to teleport your character to different sections of each level. Like the game, the two glowing colors that circle the portals are red and blue.
By creating these mirrors and placing them in front of each other, you will effectively be able to create an infinite portal. Such a phenomenon is a lot better to just look at than fall into.