I like the idea of the recipe for stone dust to gravel, but I think you might be missing a step.
Currently you have 9 stone dust → 1 gravel and other X dusts to block of X dust.
I think everything should follow
9 X dusts → block of X dust
9 pebbles of type X → gravel block of type X
Yes this does mean you need to make up a number of new gravel blocks but you can then bring back the stone dust block that was removed and it means you can utilize the pebbles you get from breaking stone tools, etc and group them into gravel.
Placing pebbles is also kind of strange, you can place pebbles and they will place themselves automatically too I believe, makes sense for the amount you get in the early game from cleaning the crucible / breaking tools. I do end up just throwing them on the ground, but they don’t seem to stack. Sure I can place multiple pebbles on the ground but the shape, or pattern doesn’t change. I think it should layer up to a gravel block as you reach 9 pebbles similar to plates and ingots.
While I’m at it I’ll rudely ask for some more blocks, could we have the ability to stack rods and long rods as we do ingots and plates? I think that would look pretty neat.