I found this interesting review on ‘we make money not art’ about combining the form and function of an old children’s toy with modern day walkie talkies. The site has a short interview with the creator of the Cup Communicator.
Its creator Duncan Wilson starts with a pair of small and simple walkie talkies, adapts them to his needs by disabling some of its functions, attaching custom controls and switches, reducing the battery size and finally changing the the configuration of everything else like the antennas, speakers and mics.
You lightly squeeze the polyurethane cup to activate the push to talk function and speak into the cup. The end of the rope (antenna) has a red LED that lights up to show you when you’re receiving an incoming signal from the other cup.