Modular movement that is fully functional standalone and interchangeable in other portable devices

1. A method for manufacturing an interchangeable movement comprising:

assembling parts into a movement subassembly, such that the subassembly is a complete working mechanism,

enclosing the subassembly in a body, and

integrating a glass with the body, wherein the body comprises a single shell with only an opening that receives the glass,

sealing the glass and the single shell to enclose the body, thereby creating a water resistant modular movement;

inserting the modular movement into a case of a portable device having a receptacle formed in an opening in a rear of the case for removably receiving the modular movement without tools and in a manner where the glass of the modular movement is visible through the case when the modular movement is inserted; and

calibrating a latching mechanism of the case to account for when the case is worn and the modular movement is inserted into the receptacle, the modular movement is held inside the receptacle at least in part by a wearer's body.

2. The method of claim 1 further comprising:

forming the receptacle in the case with a set of sidewalls whose number, shape, size, and depth are substantially similar to those of the modular movement; and

providing the case with a faceplate that aids in retaining the modular movement inside the case and defines which portions of the front of the modular movement are visible through the case.

3. The method of claim 2 wherein the depth of the modular movement and the case are substantially similar so that when the modular movement is inserted into the receptacle, one side of the modular movement is coplanar with an open end of the case, and wherein the glass that is open through the faceplate is approximately coplanar with a top of the case.

4. The method of claim 3 further comprising providing the faceplate with a shape different from that of the modular movement.

5. The method of claim 1 further comprising providing the modular movement with a subassembly comprising at least one of a mechanical movement and an electronic movement.

6. A system, comprising:

a modular movement having a body housing a plurality of layers, including:

a top layer of glass,

a movement subassembly for displaying information, including time,

wherein the modular movement includes all parts necessary for power and operation, including the displaying of the information, and wherein the body housing comprises a single shell with only an opening that receives the top layer of glass, the top layer of glass and the single shell being sealed to enclose the body housing, such that the modular movement is water resistant and fully functional standalone; and

a case, the case including a receptacle formed in an opening in a rear of the case for removably receiving the modular movement without need for a tool, such that the modular movement is user-interchangeable with another case of another portable device, wherein the case includes a latching mechanism that is calibrated to account for when the case is worn and the modular movement is inserted into the receptacle, the modular movement is held inside the receptacle at least in part by a wearer's body.