Originally posted by mirek03 its a form of lofting isn't it.., select you curves and rails (paths of sorts) and you make a surface.., for more in depth look, check your script editor for the mel. or. try the help files if no one here has an answer that helps you. Yes, it is a form of lofting. The rule is that there must be two profiles and two rails (birail), that make an enclosed, four-sided area. The curves don't necessarily have to be end-to-end, but they must be connected (not required to be attatched). When you go in to select the tool for birailing, you select two opposite curves in your four-sided shape, and then the other two opposites. Don't hold anything down when you're doing this. Maya simply knows what you're doing, and keeps the curves highlighted. It doesn't matter if the curves are straight or wavy, as long as they connect. Digital Tutors has a really good tutorial on birailing. You should check it out! Sparticus cheers!