Hi guys, I made the bottom of my part curve very slightly using the Flex feature, but now I am unable to Cut Extrude from it.

Basically I want to make a cut 1mm offset from the edge on the bottom face, 1mm deep. So it forms a lip around the bottom.

Selecting the curved face as my "Surface/Face/Plane" gives me an "Unable to create this extruded feature due to geometric conditions" error.

Not sure what I am doing wrong. Any help is appreciated!