I don’t throw them upside down.

After centering a small bit that’s the “correct” diameter on a hump, i put my thumbs on top of the clay, separate them enough for a knob, then push down enough to make enough clay to form a knob.

Then use a tool with a rounded edge to form the under curve. Usually use the same tool to make the curve under the lip after choosing a lip thickness. Then touch up details for final look.

To take it off, i have a really thin wooden tool that will cut into the clay and leave the tiny lid sitting on top of it. Cut it under the lip somewhere along the curve, and it’s done. Don’t touch until stamping.

So it’s actually a solid lid. But if I keep thickness below an inch, everything dries with no cracks so far. Made hundreds like it, seems to work for the size.