1. for a simple way
meassure the solid=>create object=> axis system
the Z axis might be the direction, but may not exactly
2. for theXOYangle from 0 to 180
for the YOZangle from 0 to 180
create an axis line with XOYangle and YOZangle
find the profile of the solid through this direction
calculate the area
next
next
compare and find the largest area
this may stupid but possibly works