Using gumball to extrude mesh vertices as points does not work directly. When only vertices are selected, using sub-object selection of points/vertices of a mesh, the gumball extrude icon is not present on the gumball axes. However, the a set of vertices can be copied to a set of points, whereupon the gumball extrusion works as in a helpful video here https://www.youtube.com/watch?v=zleUHTrTeO0