ON THIS WIKI
Magic Mirror (Thaumcraft 3)
You are now able to enchant a pair of magical mirrors that act as doorways to the void between the worlds. Anything pushed through one mirror will pass through this realm and exit through the other mirror - even across dimensional boundaries.
Unfortunately this realm is extremely hostile to mortal creatures like yourself, so using these mirrors to transport living creatures is not yet possible.
To link a pair of these magical mirrors you simply need to place one of them in a desired location. You then right click with a second mirror on the one you placed, and the pair will become linked. You may then place the second wherever you wish and items thrown into one will be ejected out the other.
Mirrors can only be linked in pairs, so while both are placed in the world and able to transmit items you cannot link them to another mirror. When you pick up a mirror it will remember the last partner it was linked with, allowing you to easily move it without having to relink it. However, while one of the paired mirrors is picked up, you may easily relink either of them.
Of course, transporting items is not free and every 16 items will consume 1 vis from the local aura.