Excellent video above, and really appreciate the signal diagram too 
It shows that three or four Castles can be used to great effect, when supported by regular video oscs and utilities.
Whilst I’m planning to build all 8 in one go, if I had to pick and choose (and already had a few oscs), the Counter, Multigate, FlipFlops and Shift Register can all be used with any signal… a mixer or two to bring them all together could be an alternative to the DAC module
The intention of the quad gate was to get more complex logic gating than just the fundamental single gates of the multi gate. I think the xor ic is the best to use, as it gives the most interesting results when you combine many signals. I use it as a kind of ‘wild card’ for shape collage inspiration.
Thanks for the insight @pbalj 
I’m even more curious to see it in action & finally get it finished.
Thanks for taking the time to draw up the diagram @sean
It really helps to mentally visualise it much better than a written description. What software did you use to create it?
To make the diagram? Used InDesign for that.