Very curious : i have absoluytly no problem with your file to use directly the Blend function!

Just click segment 1+1 call Blend
Just click segment 2+2 call Blend
Just click segment 3+3 call Blend
etc... very painful :)



Danger with Blend is that your are not sure that the "latteral sides" are always proof or intersected between them!
So you must very verify that you have a solid at the end!