My automated cobblestone harvester (easy to make smoothstone with the new crucible change as well)
What we have here is two lava source blocks, two block dispensers pointing down with redstone over them, and two water source blocks. there is also two blocks of air below the block dispenser, so water flows into it, and not out of the system.
This means water and lava will mean directly under the BD, making cobble.
And the BD are hooked up to a turntable. This isn't the optimal delay, but it works consistently, and you make plenty of cobble this way, and it's extendable if you need a lot more cobble.
A circle of 44 repeaters (21 on each long side, 1 on each short side) set on longest delay, that will repeat indefinitely once the button is pressed
Two BD set up around a turntable in a very specific way, the left three repeaters are full delay, the right one is least delay.
You place clay blocks in the left one, then press the button and as fast as they can be made urns get sucked into the right BD.
There are ways to simplify this, but this looks simplest in pictures and it took me a while to make this so maybe it will help someone else.