Note two: I write a tutorial on how to create this mod! The link is on the main page.
This mod adds a semi-renewable source of clay through a "clay sieve". The sieve converts dirt into clay using a hoe, water, a source of heat, and time.
You craft the sieve like this:
After putting it down, you can add dirt by right clicking. The dirt then needs to be "sifted" by right clicking with a hoe, and then wetted by adding a bucket of water. Then the clay needs to dry over time, meaning it must either be in the sun, or near a source of fire or lava. "Within" means in a three block square centered on the sieve, either at the same Y level or one lower. Without a source of heat the clay will never dry!
After a while, the clay will dry and the sieve can be right clicked to harvest three to eight clay balls!
Note, the drying time will be faster if a stronger source of heat is used. Fire is stronger than sunlight, and lava is stronger than fire. You only need one heat source per sieve, adding more will NOT speed it up!