Quiz Game System

Bill of materials

Here’s what you’ll need to assemble your own Kamaji buttons. The quantites shown are per single button. Multiply that by the number you need and consder ordering some spares.

Everything (except the custom PCB) can be found on Aliexpress or similar websites for cheap.

Item How many Search query
Custom PCB 1 N/A
Cherry MX switch 1 cherry mx keyboard switch
2×3×4 square LED 1 2x3x4 square LED
M2.5 6mm bolt 1 M2.5 bolt
M2.5 threaded insert 1 M2.5 threaded insert
RJ10 (4P4C) socket 1 RJ10 socket
Telephone cable 1 telephone cable 4p4c


For information on how to get the custom circuitboards manufactured, see the next section.


The Kamaji button uses standard mechanical keyboard switches compatible with Cherry MX. You can buy original Cherry switches of your choice (e.g. blue, brown, black, red), or go for a compatible alternative from Kailh or Gateron.

We would not recommend saving pennies by going with no-name clone switches. The ones from respectable brands are cheap enough, and you only need one per player button.

TODO: add photos


The LEDs in the buttons are mounted into the slot of the keyboard switch. We recommend using 2×3×4 square LEDs, as they fit well. Other LEDs with the same lead spacing might work too. For more information see this thread on Geekhack.

TODO: add photos

Bolts and inserts

TODO: add explanation

TODO: add photos

RJ10 Socket

TODO: add explanation

TODO: add photos


Now, with cables you have two options:

  1. Buy pre-made.
  2. Make your own.

The former is simpler, the latter is cheaper and more flexible.

If you’d like to buy pre-made cables, search for 4P4C telephone cables on Aliexpress or in local hardware stores.

For making your own cables you’ll need a crimping tool. Make sure it supports 4P4C plugs, not all tools do. Then buy flat 4-wire telephone cable and 4P4C plugs and crimp cables of the desired length.

TODO: Insert a photo of crimping tool, cable, and plugs.

An added benefit of having a crimping tool and plugs is that you can easily repair broken cables by trimming and re-crimping them.

Last updated on 14 Jan 2023
Published on 14 Jan 2023
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