Stair Crafting
A cobbled deepslate stair in the stonecutter would usually yield nothing, but with recobbled. one can craft it back into cobbled deepslate, or turn it into a different deepslate stair variant.
Tuff Recipe
The tuff recipe added by recobbled. Two andesite and two cobblestone craft four tuff.
Recobbled
The ability to turn stone back into cobblestone, useful for silk touch users. One may also notice that you can turn stone into smooth stone without needing to smelt it.
Smoothing
You can now smelt stairs/slabs into their smooth variants, instead of only being able to smelt the blocks they're made from. Smooth blocks can also be made in the stonecutter so smelting isn't necessary.
Slab Crafting
You can make full blocks with two slabs! Some combinations of slabs unfortunately already have recipes, and those have not changed.
Not Too Many
Normally, one can craft four purpur blocks with four popped chorus fruit. If you don't need four, recobbled adds a solution: simply make one with one!
Uncrafting
Some blocks can be uncrafted into the components that made them, like Resin Bricks, Quartz Blocks, and Bricks.