For Raspberry Pi electronics projects, sure you can always buy push buttons and wires, but why not use a more do-it-yourself construction and electronics recycling approach?
You can develop your own push buttons with ease from paper, cardboard, and aluminum foil. The main consideration when designing such a button is that you want the contacts to be relatively durable and reasonably close together so that the button is easy to use. At the same time, you want some springiness so that the button doesn’t stick down or bounce. With the right techniques, it is relatively easy to construct a reliable push button.
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Basic cardboard bench spring. You have two contacts on a base board like printed circuit board buttons, and aluminum foil on the bottom of a cardboard “bench” key cap. Pushing down closes the contacts, the cardboard ensures a reliable release.
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Paper sprung button. Similar to the cardboard bench spring, but using paper instead. Use a sufficient quantity and stiffness of paper to get a reliable spring. Use accordian folds if needed.
- Aluminum foil tube spring. This one is a bit trickier and more clever to construct, but possibly has better long term durability than the others. Strip two wire ends and wrap a tube of aluminum foil around exposed wire ends. The idea is to create a reliable electrical contact between the two wires, but due to the stiffness, springiness, and other parameters of the aluminum foil tube, it will only close an electrical connection when pressure is exerted on the tube. The whole construction itself should be inside of another enclosure such as a paper sleeve, behind a cardboard key cap, and so on.
If you pull wire out of random old electronics or phone lines for use in electronics projects, there are some considerations you need to keep in mind for this. First off is the stiffness of the wires. Wires designed for long cables are generally more stiff than would be ideal for working on an electronics project, unless you are specifically intending to use such wires for long cabling. However, if the wire is for “patch cable”, the stiffness may be entirely contained in the insulation, and heating it up with a soldering iron may be all that is needed to bend it into the required sharp curves for your electronics project interior. Verify that the interior is composed of stranded wiring, not solid core wire.
Phone line wires will be tricky to work with because the strands are not twisted together, so when you strip the insulation, you need to twist together the wires before working. Also, you need to be careful not to strip out too many wire strands when stripping off the insulation, otherwise you should try again on a new cut.