I'm creating a 3D model of an LMI chemical feed pump. The pump has a fitting on top which has a knob show in the attached photo. The knob has a teardrop shape and curves in two directions. If anyone can help me model this knob or give me some suggestions, I'd appreciate it.Thanks.

You'll need to create the profile of the knob looking at it from the end.  Extrude it.  To get the curved face use the Slice command and an arc (Object or Surface option should work).

Something kind of like this.

Or more like this.

John:That looks great. I've created the profile and extruded the teardrop shape. The problem I'm having is using the slice command with the arc. When I use the Slice command all it does and slice the teardrop in half. I don't get the contour change that I need.

You must have the arc in the wrong position relative to the model.  Change it.

Got it! Thanks so much for all your help!