This is a simple idea for anyone who uses billets in their magic and mentalism. In fact it's such a simple idea that it must have been mentioned before in some classic mentalism book that I've never read. But if it has been then people clearly missed it because it completely solves one of the issues people have with billets.
What should you use for a billet?
Some people use their business cards. The argument against this is that you shouldn't fold or tear your business card because you're essentially not respecting your own brand by destroying this thing that is a representation of you. I don't know if I believe that. That seems like some voodoo shit. But I don't completely disagree. Your business card also might not be suited for billet work. It might be too thick or an odd shape. Or you might not even have business cards which is more of an issue for the amateur magician who is my target audience.
Some people use blank pieces of heavy paper, perhaps on a little pad that they carry with them. Do you want to carry a little pad along with you? Are you trying to get beat up? "Where's my little pad! I thought I put it in this pocket with my coin purse." No, the little pad or stack of blank business cards is only acceptable in a formal show where you're expected to have props. For the casual performer these things are a no-no.
So what do I suggest?
Uhm, Andy, that was the first thing you mentioned, dingleberry.
Oh, right. No, I don't mean your business card. And I don't mean going to the Chinese restaurant near you and grabbing a stack of theirs. I mean going to Vistaprint and spending 10 bucks to print off 500 business cards for a real or fictional third party and then using those when you perform. There are some obvious and not so obvious benefits to this.
1. You're not destroying your own business card.
2. You're not carrying around a little pad of blank paper like a little fancy-boy.
3. It's a normal object that you would expect to find in a wallet.
4. If you use your business card or a blank card then the idea of duplicates is inherent in the prop itself. You don't ever buy just one business card, or one piece of blank paper. These items only exist in multiples. So it's not difficult for a spectator to hazard a guess that there might be a switch involved. Alternatively, if you open your wallet, flip through some stuff, and toss out someone else's business card, this feels much more like it's the only one of these that can possibly be in play. Want to ramp up this singularity even more? Take a pen and write "4:00 Tues." in one of the corners on the business card. Do the same on a pre-folded duplicate. You can now switch these in and out and a duplicate will be so far away from people's thoughts.
5. They can be an unspoken status symbol. Remember, you can create a business card for anyone you like: someone prominent in your area, someone in the entertainment industry, someone in politics. You don't make a big deal about this. Let the other person mention it. For example, maybe I'm about to show someone a trick, I open my wallet looking for something for them to write on and toss Elon Musk's business card onto the table and say to myself, "yeah, I don't need this...." The other person might look at the card before or after the effect and ask why I have it. I'd just be like, "Oh, we were at the same event a couple weeks ago. He wants me to do his Christmas party this year. But that time of year is all about family for me. And as far as I'm concerned, fossil fuels are the future."
6. For me, this is the biggest benefit. Your business cards and blank pieces of paper are presentational dead ends. But you can create a business card to use in one effect that could lead the conversation in any direction you'd like it to go for a follow-up effect. You could have a business card for someone at the FBI, for a parapsychologist, for a futurist, for a casino CEO, for anybody. Why do you have this business card? You've been asked to consult, or give your input on a project, or they want to study you. Whatever, but it's all very fluid. If you're going to perform more than one effect in a casual situation then the transition has to be completely natural, and this gambit allows you to seamlessly flow into any other type of effect.
Now obviously this isn't the solution for an effect that requires a lot of billets ("Why do you have ten business cards for Alan Thicke?"). But for any center tear, peek, billet switch, or even just an effect where you're writing down a prediction, a sham business card can be a valuable tool.