You'll want to get it from a pottery supplies place. You def want something with very little grog in it. That is basically the rough part of clays. Porcelain has very little. Stoneware tends to have a good bit.
Not sure of any other details. Thats just what I know from having done ceramics and hanging out here. Clay/mud is generally not my thing.
+1 on the pottery supply store. You should find a place you can drive to because shipping will be out of this world.. Powder clay to look up for are Kaolin, ball, red art.. maybe some bentonite ( less coverage). Safety when mixing is very important.. wear a mask!! The dust floats everywhere and will stick to your lungs.. once wet it's fully safe. Mix in a ventilated area.
Love you, too
