This many years along, (8?, 10?) I have made a number of magic mirrors. My first one I took an empty picture frame and spray painted the glass flat black. With cleansing and consecration, it was sufficient. I have used new mirrors and old ones. I have come to prefer antique mirrors. I often don't cleanse them at first to see what is in them. This could be a bad thing for someone with inadequate protections, so I don't recommend it, but it is interesting for the hardy of spirit.
Honestly the mirror makes a lot less difference than the user. An inexperienced user can have a great mirror and get poor results. I have learned not to do work in the mirror for people, opting instead to teach them how to do their own. For beginners I suggest to put a nonagram on the back of the mirror, and one on a cloth on the front, and keep it closed at all times not in use. This keeps unwanted things from finding their way in and out of it. My working mirror is that way now.
The trance practice is the most important part. I set up in a dark room, light two candles that light the mirror, but not me, and focus. It takes more or less time to reach the place where my image fades, and I start seeing what is in the mirror. Depending on why I am there, I may be doing this in the trance phase of a ceremony, or other times when I have a question. I have several regular spirits I meet there, and if I have gone in ceremony, I often meet someone totally unexpected.
It is important to remember, if you have used protections, whoever shows up is there because you asked them to. One time I made requests and started trance, and this green snake woman, with snake hair showed up. Honestly, I have no clue why these creatures choose to look like this, but it is their way. I knew this stuff happens, so it did not take long to regain my composure and begin the conversation. She seemed amused.
Bear in mind, if you use a strange mirror, uncleansed, without protections, that these things are doorways, and they can let some really evil stuff in. Know to open and close them, and to seal them with nonagrams to prevent surprises. It does not seem to take a lot, but in my working space, with my usual protections, I have never had a bad experience.
I have heard friends that will not allow a working mirror in their houses after bad experiences. Some have seen things they still whisper about, and some have had to have things cleansed from their houses. This is not a toy. This is a doorway, and improperly used it opens the way to things unbidden. It is the spiritual equivalent of leaving your door open in the bad part of town, you could get lucky, but do you want to count on it?
Blessings
