Would be cool if it was possible to make even crazier contraptions by allowing some more fine grained redstone controls; for example:

• funnels, tunnels, chutes, portable interfaces could be disabled via a redstone signal
• something like a redstone gearshift but that enable/disables rotation instead of switching (quite useful for fine-grained disabling bits of your machinery)

all of that, except for tunnels and portable interfaces, already implemented

ah, interesting, I tried disabling funnels and it didn't work, probably I did something wrong. what would be the block that disables rotation given a redstone signal?

a clutch

Awesome, thanks! I will close it as this was mostly due to my ignorance about what already existed.