How do you cope with simple geometry to make a tube, ie two circles traced consecutively and then extruded. Ive tried a circle then the offset curve tool but I get two different circles that are not linked, In Viz there is a command for the second circle to be part of the first circle geometry and afterwards one extrudes (l'ensemble), but in Maya I havent found such a command. I enclose sketch to illustrate. It would be good if the answer could be applied to a square as well .