In the Form contextual environment, Thicken duplicates the selected surfaces and offsets the specified distance.
Design > Form > Modify > Thicken
Enables the selection of the T-Spline body to thicken. The body can be an open or closed surface.
Available when Direction is set to Axis. Enables the selection of the axis to control the thicken direction.
Specifies the distance to thicken.