A) Are you trying to extrude a face, or close a volume?
B) If the surfaces do not close, there is almost a 100% chance that you cannot use them to split (without extending them) A gap would also represent a face that does not completely intersect the part that it is cutting
sorry, if the question was not clear.
i have closed faces and i want to create a solid.
i mean, in v4 you could do in this way:
create a volume with closed faces then a solid by solid/complex/volume.
how to do in v5?
best regards
fabio.