Accepting that one of the main duties of an architect is mastering the tectonic expression of the building and its architectural effect, could there be a mechanism that allows a building or object to change its expression? Could the envelope of a building respond to its exterior context or internal function by changing its appearance? How can the elements of a building screen - whether in wall or roof - change their orientation and configuration to express a response to environments inside or outside? We know that the modern ideas of "wall-free structure" and "transparency" have begun to change the concept of building envelopes. These changes have allowed envelopes to become lighter, less opaque, and more flexible; and as a result the architect has more freedom in exterior expression. In the Seagram Tower, for instance, while I-beams emphasize the vertical effect of the tower, the glass envelope allows the building to change its surface effect from day to night. Having more freedom in the exterior expression of buildings has not only brought transparency but also opened a door for a greater interaction between inside and outside. If, in the past, the exterior walls of a building, limited by structural needs, had to carry its weight, today, analogous with living nature, the use of a structural skeleton gives much more freedom of expression and interaction to the exterior envelope of the buildings. Rooted in the ground and running through the building's mass, instead of outside it, the skeleton takes on the load of the building, and masonry walls can be replaced with partitioning envelopes that are open to freer interpretation. Influenced by engineers and architects like Chuck Hoberman and Santiago Calatrava, my areas of study since 1997 have been focused on the subject of movement in structures and kinetic architectural elements. I have approached this subject from two points of view. While my first study models explored the ways structures can be folded and transformed, this book is about the investigation and study of envelopes and tectonic planes that can be manipulated through operable mechanisms to change their interior or exterior expression. This study is based on the separation between the mechanisms which are the cause of the movements in the models and the kinetic planes in envelopes that have the duty of interaction between inside and outside. If folding of structures in the early stages of my studies resulted in "metamorphosis", my current work is about studying mechanisms that change the surface of an envelope and result in "transmutation". / Master of Architecture