In vanilla when you start clayforming the game puts down 64 voxels in an 8x8 grid and then gives you 25 available voxels, and adds 25 more each time you run out by taking a piece of clay from the stack you're currently holding.  This means that you can make anything with 89 voxels or less with just 1 piece of clay but that things that take a lot more voxels will take proportionately many many more, making it less efficient to do recipes with more clay in them than the basic ones.

I've changed it so it puts down 36 voxels in a 6x6 grid to start and gives you 0 extra and adds 36 more each time you add another piece of clay.  This has the effect of making some of the smaller recipes more expensive (a crock takes 3 clay now instead of 2) but in turn it makes the bigger recipes a tad cheaper, and more efficient to make (4 crocks take 11 to make instead of 14) meaning that you're not punished for doing the recipes that produce more.

I also added a few extra shingles recipes so you can have more options on how many to make.

It also has compatibility with the simple pottery wheel mod, changing it to use clay consistently but making it so that each clay item only gives you 30 voxels.  Meaning the automation of the pottery wheel has a slight detriment in material cost.