NOW, taking a self-critical viewpoint:
Getting this '4 signal BUS' to work is nice project milestone, but also establishes challenge: To make that series network to function with less.
To that end, consider a 3 shaft SERIES BUS:
You would 'encode' one of 4 (outputs), using two shafts, plus a needed clock (mechanical shaft). The two 'addressing bits', using CW for '1', or CCW (counter clockwise rotation, to a stop), for positioning a multiple selection switch, then pulse the mechanical 'clock' line, producing (rotary) output, on the one of four.
This won't work, in extension, as each new access, further down the series string of switch box stations will require yet more and more 'bulk' of switching activity. Or, say, it can work but ridiculously burdened.
Each access, let's say you are at station 7; now to control and access the next, station 8, you need station 7 multiple times, for twirling those 3 inputs to station 8. But for that, you have to revisit station 6, multiple times, and for that you need station 5,
...and for that...station 4, etc, etc etc.
Gets to be a factorial number, of sorts, and the result is a (very) non-linear pile-up of required access/outputs, in the rotary encoded digital switching scheme!
In current design ( 4 shafts total travel down the network line), a station count, like 30, is going to mean TWICE as many pulses issued by base control, VS having 15 stations, for example.
I also, here POSTING A PICTURE, OF A BUG, as I have no picture of CAT.