Recently, my Auckland Transport key tag stopped working, and since they’ve stopped selling the key tags, the only alternative was to use the larger AT HOP card.
I wanted something more compact and unique, so I decided to convert my bus card into a turtle keychain. Here’s how I did it:
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Dissolving the Card: Acetone can be used to dissolve the plastic on the original key card. This take about 30 minutes and then you can carefully pull the chip and coil. Remember to cover your container so that the acetone doesn’t all evaporate. I also used a coin to add weight the card and submerge it in the acetone.
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Replacing the Coil: Once the chip was free, I cut the wires near the chip so that it could be attached to a new RFID coil. I ordered these from Alibaba, and soldered the bus card’s chip onto the new coils.
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3D Printing the Turtle Casing: With the chip and coil ready, I used a scaled down version of this turtle case which is actually intended for airtags but worked perfectly for this!
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Encasing the Chip and Coil: After printing the turtle casing, I used resin to encase the RFID chip and coil inside the turtle. This helps keep everything secure on the inside of the turtle but is hidden once the turtle is assembled.
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Final Assembly: The final assembly is a much smaller and more portable version of the bus card, and it definitely gets some strange looks from the bus drivers!
