The outdoor switch was made using an IP rated switch (available all over the place – look for foot/palm switch) and then that just acts as a contact for a cable to an arduino.
the arduino needs to be the right type .. i think the pro micro and or leonardo are fine .. but essentially you are looking for ‘keyboard emulation’ so that when two of the pins are connected (by the button) the arduino runs a little script essentially ‘pressing’ space bar …. or a key of your choice .. so that Rightbooth sees it and triggers the photo
the arduino is connected by usb to the pc .. and will be recognised as a HID or Human Interface Device … its also powered this way .. so it depends on your setup where and how the various items are placed – there are loads of sensible ways to ‘debounce’ the signal incase you are getting loads of triggers – but i didnt need to bother as rightbooth was happy just seeing the ‘spacebar’ once and getting on with it. 🙂
you can also buy fairly inexpensive ‘keyboard emulation’ circuits – used a lot for DIY arcades etc .. which dont require much setup.