Hi I've been designing an experimenter's box having a misc set of five circuit boards, taken out of small toys.
For selections each 'Channel' input has a 1 of 12 rotary or rather a six position having also a SPDT toggle.
So, for example CH4 is a 'Singing Bird' with motion detecting sensor input. Now that input can be from any output, excepting itself.
An experiment could involve connecting to a latch, such as CH2 in my design. Today, I am wiring in 12 separate outputs for the various (5) channels. The toy Bird has 3 outputs, including Audio Out, and two pulsed outputs driving solenoid coils: the coils move the Bird's
beak and neck during a few moments of song.
Readers, if you can follow this, you see that those three outputs create interesting / complex signals that are yet again available to any next device (channel). I even realized that CH5,. a "dog barking' audio circuit taken out from a stuffed toy will accept an AC waveform, to the 3VDC power leads, within reasonable reverse voltage limits, as the original toy used reversed voltage for control of a separate motor. So it worked !
Now that outcome was unexpected; having the "dog" circuit playing the bird chirps in a sort-of modulation effect. I figure there are more than 500,000 ways to dial in your semi-random layout order.
Let your 6 year old future engineer go hog wild, dialing those 5 rotary switches in harmless interconnections !