The one thing you DON'T want to do is bring out the key and make it perform. You need to come up with a reason to bring out the key. You can make a box with a keyhole in it and just pretend that the key opens it, for example, but you must have a reason why you need the key. The key's movement is an embarrassment to you when it first happens. So that means you need to explain why it does that (the routine). If it scares you, it will start to scare them. If you know how to make the key move while in their hands, you can snatch it away from them for their own safety and put it away before "anything happens."
There is a book edited by Steve Drury, called Key Mysteries (still available via Lulu I believe). Next to a lot of background, it also contains quite a few routines, by Ed Solomon, Christian Chelman, Prof BC and many others. I can recommend it. There is an earlier book by Ed Solomon, called 'What Lies Behind - Presentations for the Haunted Key'. It is out of print and unfortunately I don't own it. A couple of months ago I found a magic shop in Singapore that said it had the book. But their website wasn't up-to-date... Cheers, Luc.
Apologies if this is teaching anyone to suck eggs but the best advice I had re the use of my Cemetery Gate Key was to take a look at the video on Ray Carlysle's website here:http://www.carlyletouch.com/mental_key.html
This really helped me to bring my key to life.
As somone who had a misspent youth spending nights in "haunted" houses I can often fall back on recorded cases to make a particular effect that bit more believable. I was lucky enough to spend a night in a "haunted" Inn where two of us heard the sound of a key turning in a lock and a door opening between us. The door had been removed many years earlier. (I'm still going with the stone tape theory) I can bring my CGK out and explain that this was one of the original keys to that door, the story is usually enough to get the hairs going up on the back of their neck but when the key turns in my hand or theirs it's worth it's weight in gold! Best bit is that it still puts the shits up me so no acting is required!
I believe the best routine would be one you come up with yourself. Something that relates to you, your interests and one which can touch others. I am here to help in any way I can. Please let me know more about you and what you intend the routine to be, and I will try to come up with something. Do you want it to be about spirits, ghosts, the power of memories, residual energy, the power of the mind, or something else?
I was thinking along the lines of a cemetery tomb key that responds whenever a loved one in the vault is mentioned and remembered. They then return to turn the key and remind the loved one that they are never really gone as long as they are remembered.
Your idea is wonderful! It is bizarre (the tomb, the deceased...), it is emotional (because it is about a loved one), and the message (about everlasting love) is also wonderful. Many congrats! The only slight problem I might find, is if you are thinking about doing this about a participant´s loved one, because then, the Randi´s of the world may be after you, as if you are a fake médium type of situation. If you do it with a pre-established backstory, then you are pretty much covered, because then, no participant can claim you as a fake médium, since you told a story which is not about their loved ones. A way to get around this, is if you tell the participant to hold the key and think about their dead loved ones, and the power of the love between them will manifest through the key. As that would not be a spirit manifestation as such, you would be safe from said problems. If I did misunderstand your idea, please let me know more about it, and I´ll add more thoughts. An idea for you, is after the key moves(preferably on the participant´s hand), as if opening the door to the spirit world, you can use the key on a string as a pendulum to answer questions (the pendulum on the participant´s hand). I love pendulum work, and it is quite amazing, the type of response it is capable of. If you don´t have any experience with pendulums, let me know and I´ll send you my little PDF, which I wrote for free distribution among ou little community. If you want our conversation to be more private, we can do this by P.M instead, but I believe the ideas being shared here can benefit others. I´m glad I can be of any help. All the best!