Interactive mesh editing techniques that preserve discrete differential properties are promising to support the design of mechanical parts such as automobile sheet metal panels. However, existing methods lack the ability to manipulate form-features and hard constraints, which are common in engineering applications. In product design, some regions on a 3D model are often required to precisely preserve the surface types and parameters during deformation. In this paper, we propose a discrete framework for preserving the shapes of form-features using hard constraints in interactive shape deformation. Deformed shapes are calculated so that form-features translate and rotate while preserving their original shapes according to manipulating handles. In addition, we show how to constrain the motion of form features using linear constraints. The implemented system can achieve a real-time response for constrained deformation.