[wdswnjsa] Sanding an extrusion

Extrude a flat shape into the third dimension.  Algorithmically round off the sharp edges along the front and back.  Let's say the bisecting plane must remain exactly the original flat shape.

It might be elegant if thin parts in the original shape became thin along the third dimension as well.  Perhaps something like: start with the two dimensional region.  Pick a point within the region.  Construct the largest circle centered on that point whose interior is wholly contained within the region.  Extend the circle into a 3D ball.  The final 3D object is the union of all balls around all points.

Inspired by wanting to create a sculpture of the symbol pi.