The Unfold sheet tool is used to flatten analytical or NURB surfaces into the xy plane. The unfold operation works on a sheet body that is flattened by mapping it onto a plane. The output body is a B-rep body consisting of planar faces and edges.

If the input sheet body is stretched and/or compressed during the unfolding, the shapes of features on the input body will be transferred faithfully to the output body, at the cost of some area distortion. The amount of distortion depends on the curvature of the input sheet body, as well as the constraints imposed by how faces are connected. Developable Surfaces (with zero Gaussian curvature), such as cylinders and cones can be unfolded without any area distortion. Other curved surfaces (with non-zero Gaussian curvature) may have some distortion during unfolding.

The unfold tool is in the mechanical tool palette located under Tools in the menu bar. Selecting the tool icon prompts the user for the surface or body to unfold. The surface to unfold fold must have zero thickness such as with a surface or mesh object. For example, it does not accept a solid. Select any surface in the body and the results are displayed in the XY plane at z = 0.

The unfold result will have the same area unfolded as folded.