Introduction: DIY Self-sorting Bank

Don’t you also come frequently come against this annoying event of everyday life. Having to search all over the place for those 25 cents and mistakenly taking for the 100th time a 5 cent coin? Well you are not the only one. This project tries to solve this problem by creating a self sorting coin bank. With this project no need to waste 10 minutes finding the change for the bus ticket you can easily find exactly the amount you want. Each coin having its own place. To do so we created a box with a slope for the coins to slide on. In this slope are holes of different radius, placed from smaller to bigger. Each coin having its own dimension the small ones will fall in the first holes while the big one, too big for the holes will continue sliding on the slope until they fall in the right dimensioned hole. It is really simple to use, you put your coin in a small funnel placed at the beginning of the slope and the coin will slide along the slope until it falls in the hole corresponding to its dimensions. When they fall in the hole a little LED will light up, it unable to see which holes have coins if their are no coins no light will light up. Also, all of the material of this project is easy to find, ecofriendly and simple. No need to stress when everything is DIY.

Step 1: What You Will Need...


  • Scissors
  • Knife blade (exacto)
  • Hot-glue gun
  • Screwdriver
  • Monkey wrench


  • Metal rings
  • Cartboard
  • Paper
  • 3V lithium batteries (5)
  • LEDs (5) (here red)
  • Plastic water bottle
  • Sticky tape
  • Sharpie (black)
  • 0.2mm radius bamboo sticks (length depends on bank dimensions)
  • Rubber bands (2)

Step 2: Our Inspiration

In this document, you can see a picture of our inspiration of the design: pretty simple, classic and cute.

Step 3: The Bank and Its Creation

Step 1: Preparation of the material

  • The proportion of the bank are decided, cut the pieces of cardboard. According to the 3D model the pieces of cardboard the dimensions depend on the decision here 10cm wide by 15 cm (top part to 8cm bottom part and 30cm length.
  • Secondly, prepare the metal rings, with a monkey wrench tight them to the dimensions of the coin each value of coin needs an adjusted ring (Here 5, 10, 25 cents and 1 and 2$). Glue one of the two branch of each LED to a lithium 3V battery, caution to test first that the right branch is placed on the right side of the battery.
  • Finally, cut the plastic bottle bottom and upper parts, and secure the edges with sticky tape. Pock holes on both sides of the bottom part of bottle. The hole must be wide enough for the bamboo stick to fit in.

*In the files (up), you can see our work as a 3D design innovation. You can also see what you should do with your monkey wrench.

Step 4: The Bank and Its Creation

Step 2: Assembling the pieces

  • Following the 3D model, Assemble the different piece of cardboard. For this, first, with the help of a hot-glue gun glue the pieces together except the top part with the holes. Then Glue the metal ring to the holes, ensure that they are well fitted and glued. Caution, don’t let hot glue fill the metal ring because it will change the width of your hole and the coins won’t get in.
  • Once the metal ring are glue to the cardboard piece, glue this piece to the rest of the structure. Finalise by securing the joints with sticky tape. Cover the defaults do to the embedment of the metal rings with duck tape. Glue the batteries and LEDs beneath each hole, the glued branch of the LED should be glued to the cardboard (the video is in the top section).
  • Finally glue the bamboo sticks and the lower part of the bottle. The upper part will serve of funnel and the sticks of ramp to prevent the coins from falling off.

Step 5: The Bank and Its Creation

Step 3: Finalisation

On a white paper right the value of each coin and stick it under the right hole. Using another piece of paper, cut a piece of paper with the same dimensions you used for the top part of the bank (the one with holes) stick it, it will diminish the coefficient of friction of the tape and enable the coin to slide down the slope. Glue two piece of rubber band to the end of the slope they will be used to maintain the bottom part of the bottle in case an error occur while the coin slides down the slope.

Step 6: Conclusion

During this problems a few problems were encountered some with which we dealt easily others less.

  • First when constructing the bank embedding the metal ring to the cardboard was more complicated than predicted as the pieces weren't perfectly round, so we had to cut multiples time for it to fit. But consequently, sometimes we cut too much of it and there were holes that we had to conceal with sticky tape. There isn’t really a trick for this problem just patience and not be discouraged.
  • Another problem we faced, was that when the project was “finished” the tape that we had put to deal with the first problem increased the coefficient of friction of the cardboard and prevented the coins from being able to slide down the slope. To solve this problem we had to increase the slope and be able to change the surface material of the slope. To do so we cut out a piece of paper and the holes in the right dimension and glued it with hot glue. As paper coefficient of friction is smaller it unable the coins not to “stick” to the surface and slide down.
  • Finally we added a little cardboard piece beneath the bank so that the slope would increase. A lot could be improved as in any project, for example we could improve the disposition of cardboard walls separating the coins as small holes make that sometimes the coins get lost between the spaces. Secondly, we could improve the holes some of them were less well made and the 10 cent hole is too close from the funnel which prevent the coins (sometimes) to fall in the hole.

Step 7: Some Videos to Make Things More Fun


ThirdEarthDesign (author)2017-05-14

Nice build, now all I need is some money :-)

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