To use Lathe tool inside modeler
Multiply > Modeler > Extrude or press shift (b)
If you would like to use the Lathe tool, the first thing to do is to choose the Modeler option from the Multiply menu. Later, you need to select the Lathe option or press the shift (b) to select the Lathe tool. It’s used to join the shape that is created in half way.
If you would like to create a vase, first, you can draw a flat point to represent the half shape of the vase by using the point tool. After that, you need to use the lathe tool to joint the point into 3D vase model in only one drag.
You just need to point and drag the mouse.