A relative was recently diagnosed with pancreatic cancer. There was a
need to be able to alert a caregiver (in another room) day or night when a need arises.
I bought a smoke detector and a remote control switch in the evening (overnight from Amazon) and designed/printed and assembled the box the next day. Push the button and power comes on the box, which causes the smoke detector buzzer to sound.
For power, I used a 9 volt wall wart (8.4 volts actually). This was a salvaged power supply from an old video camera which had died. I always save the power supplies from dead electronics for future projects.
Remove the buzzer/electronics from a smoke detector.
Find the test switch and (on the back) close the open terminals with a permanent solder connection.
Print the box and lid using the files given here.
You can also have the box printed locally by finding someone using http://www.3dhubs.com
Solder the wires from the power supply (I used a power supply "rescued" from dead electronics).
Place the buzzer inside the box.
Close the lid and plug the power supply cord into the remote control switch receiver.
I used this:
Push the "on" button on the battery powered on/off switch. This will supply power to the call box and the LOUD alarm will start beeping within a few seconds.