Instructables
Some people carry change purse with them where ever they go, but you won t use most of those coins. Why carry coins that you won t use? So what is the fewest number of coins you can carry that allows you to produce any exact change? And then find an inexpensive way to carry that in your wallet.
 
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Step 1: Theory

So what is the fewest number of coins you can carry that allows you to produce any exact change?The answer is 10 coins, 3 Quarters, 1 dime, 2 nickel, and 4 pennies. With this combination you can produce any number between 1-99 cents.

An alternative answer would be 6 coins, 3 Quarters, 2 dimes and 1 nickel. In this example you will range most change between 5-95 cents, in 5 cents increments. In this example you will never receive more than 4 cents in change back.

The project is a way to carry these 10 coins easily inside your wallet. I have used a thin piece of cardboard. But if you may use most anything, I recommend any material about 2 stacked coins thick, and have enough friction to hold the coins in place.

Step 2: Materials:

a Credit Card to draw template
A pen
3 Quarters
1 dime
2 nickels
4 pennies
sharp knife
Thin Cardboard
30 minuets to an hour of free time

Step 3: Draw and cut

First get the cardboard, use a credit card and your pen to draw a template.

Step 4: Draw your coins

Place coins on template. Use pen to trace your coins. Put them generally where I have them place. Now when your tracing remember the cardboard must support itself when you cut the coins out. So don t have coins touching and leave a fair amount of room between them. Remember you will be staking the coins 2 per slot.
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buck221722 days ago

How about using 2 old credit/ATM cards stuck together but offset the holes slightly so that you can push a coin in from each side but they won't go the whole way through. That may cure the push right through issue. I may have a play and see what I can make and then post--- so many ideas/projects, so little time

This would also be handy for parking meters.
seawee651 year ago
This is awesome!
grimpirate2 years ago
A paper model that uses this instructable as a basis to make another version:
http://www.papersmithforge.xtreemhost.com/index.php?i=8&j=9cd4
BLUEBLOBS22 years ago
This is way cool! I made one with 4 pennies, 2 nickels, 1 dime, 1 quarter, and 1 half dollar.
vancester2 years ago
I think the FEWEST number of coins would be 9 if you replaced the two quarters with a half. Although it may not work with a pop machine.
15zhangfra4 years ago
what about putting another very thin layer of cardboard or stiff and strong material to back it, so that the coins can only come out one side. slightly harder to get out, but less likely to fall out.
I was thinking something similar to your suggestions. I think you can use clear packaging tape to cover the holes completely on one side and about half of each of the holes on the other side. And you can dispense the coins out of the half covered circles but it would be hard for them to fall.
Ian M5 years ago
I've heard that when people used payphones, they would carry a quarter in these in case of emergency. Nowadays, it's probably easier to find a coin on the street than a payphone; so it's probably better to carry a payphone with you.
What's a payphone?
an old phone. you insert a certan amount of money and then you can call someone with it.

i think there found in the city. Like New York.
i wouldnt know though I live in a neghborhood.
cl0ney Ian M4 years ago
lol... that's way cool. well said. :)
cl0ney cl0ney4 years ago
oh yeah.... forgot to mention that the other day, I broke down and my phone was flat. I walked for quite a while looking for a payphone and ended up returning to my car, an hour and a half later, only to ask someone to use their cellphone. This was in a very populated suburb of Anaheim, CA. Long story short, compassion (which seems rare these days) is likely more frequent than a payphone.
why was your phone "flat" most phones are made in 3 dimensions arent they
He means the battery was dead
In the case of payphones, 911 is a free call. 
blodefood Ian M4 years ago
It's 50 cents where I live.
 That's what she said.
bowmaster Ian M5 years ago
LOL!!
Redgerr3 years ago
i really like this idea and think i might make one for myself. i was reading the comments and am considering making sort of a sleeve out of something thin (paper?) that would go around it... that might make it slightly more useful so that change dosnt fly everywhere.

anyway... thanks for the great instructable and i hope to see more useful ones later
D00M99 Redgerr3 years ago
I think that's the purpose of the credit card shape; so that you could fit it in the credit card slot which would act as a sleeve anyway. Until you pull it out. :P
hansonsux4 years ago
I just bugger them with dollar coins. 
What about the two dollar coins?
 Toonies you mean
zascecs4 years ago
 Wow! I would have never thought of this! And what a great idea; I really need one of these...
fozzy134 years ago
Genius!!
beantown534 years ago
Nice idea. Well thought out and executed. Has room for improvements.
I have a suggestion to improve your coin layout slightly.

Where you have the two largest coins next to each other I noticed that one has gone off the edge of the card, If you arranged the coins so that the biggest coins are not put next to each other, you would avoid this. For example, have the dime in one corner, then the pennies or the nickel adjacent to it, then the others where they will fit.
cupojoe9995 years ago
do the coins stay in place or will they fall out easily if turned up side down. and if so could 2 rubber bands (the wide kind keep them in place?
Meragness6 years ago
what a cute instructable!! yet I don't think it can be a TRUE instructable until some seriously complicated...math...measurements, and waiting-to-dry is incorporated to the procedure. I swear, every time i read an instructable it's like the longest and hardest process to make something that you don't need anyway. I just admire the finished product and wish I could have had the initiative to make one myself. Call me lazy
lazy
Kaiven5 years ago
I am doing this.
freakinhuge5 years ago
Did you know that you can put those cut out cardboard quarter pieces in those little candy / bouncy ball machines near the check out at grocery stores? Not saying that I do or anything ;-)
Lilliepop6 years ago
Why can't you just cut it out of those old crappy fake credit cards you get in the mail? a few of them glued together almost makes it worth while. i say good job! this is one I will go out and try. I have a pretty thick wallet and hate clinking change.
tinygirl5056 years ago
Seven US coin version: four pennies, two nickels, one dime. Then, you give only as much change as is over the nearest multiple of quarters. So, for example, if the charge is $12.38 you pay $20.13, and get $7.75 Your change back will always be in multiples of 25.
What I'm wondering is, a little more than a year later, is this thing still holding up? I would think the coin holes would lose their tightness. Though obviously it's not an expensive project to re-create.
RTourn (author)  FunkLiberationFront6 years ago
Honestly I don't use it, it just takes too long to bring it in and out of my wallet. What I do is grab the coins from my car before I enter the store. My goal now is to carry 1 quarter, 1 dime, 1 nickel, and 4 pennies. I have to do some quick math at the counter but I can always get quarters back.
awsome! now all you need to do is spray paint the card board the color of your wallet like i did!
Goodhart7 years ago
Hmm, presently I do use a squeeze-open coin holder. They last a number of years, and I rarely have a lack of change or too much for the holder. This idea, would be great if it improved somehow on what I already use, but I can't personally see an advantage with it at this time. Now, that mechanism that the Bus driver carried at one time on his belt....that would be something to have (albeit a bit bulky). :)
csmithblues7 years ago
whats really funny is that i spent the time to read all of the comments.
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