Extrude curve circularly having consulted How can I extrude a dome from a circular face?, I realize I could probably use that method to achieve what I'm looking for (a stool cushion). However I already have a curve with the wanted form and was wondering if there's something like a circular extrusion.
You can try to convert the curve to mesh and then just extruding to the shape you want converting the curve to mesh shortcut is alt+C i think  but maybe there is better way how to do it is long time i use blender