I want to store, on my person, coins with different years on them. The produced coin will match their year of birth. Does such a thing as a coin index exist? Not found one yet.

How many coins would you need? If you ask me, to have a variety of years is going to be on the heavy side to carry around. An interesting idea, though I don't think it would be practical.

The only coin index that I know of is the one that helps you quickly count out change while in your pocket. That one will probably not be of help. I imagine you could make an index with a piece of stiff cardboard and some elastic. Perhaps you make several boards and position them in various pockets?

Perhaps you can have an index of dates, and a bowl of change. One coin picked at random, and you have predicted the date.

Thank you for your suggestions. Yes it sounds wildly impractical and probably is, but I'm foolish enough to test it out. The participants would occupy a narrow range of DOBs (I hope!). 20 years perhaps. So the stiff cardboard idea sounds suitable.

As I picture it, you could even make the index 2-sided, with coins on each side. Maybe odd-numbered years on one side, even on the other?

How fast do you need to access the coin, and what kind reset are you OK with? Because one "simple" option would be to get a stack of magnetic quarters (not cheap) of each year and keep them in order in the stack.
Reach in your pocket, count off the relevant number of years, and there you go.

Pricey, and slightly annoying to reset, but it would take the least amount of pocket space.

Ask Tony Miller - he likes indices

DIY - think about the Deal Dill trick with the notebook and an envelope

Of course speed is important, however, depending on routining, covertly obtaining the spectators year of birth may not necessarily require speed. Accessing the index need only be natural, the spectator doesn't know where you are going with the effect. Example, 1st obtain the spectators date of birth covertly. ask to borrow a quarter. Talk about the quaters, try to get some sort of reading based on the quarter, Reveal that sometimes a borrowed quarter doesn't reveal anything... then act startled... wait a scond.... what year were you born? Tada....

I have been seeking this exact same thing. For 100 coins. Looks like I will need to have it fabricated sadly.

Coin shops already have your index for you. They sell those cardboard coin displays. Like the March of Dimes. Where id just holds the bottom edge of the coin.

Maybe a force of the spectator's date would be easier. I've been playing with which state quarter corresponds to 1-52 which led to a deck of playing cards has 52. Etc. I ended up going to a cloth bag with 2 compartments.

Another idea was in a briefcase for platform.

Sorry. Index in the briefcase.