You create parts and subassemblies in part files, or in place in assembly files. The features of components originate as sketches that you can fully or partially dimension. To specify feature volume, you use feature-creation commands, and supply key values. To resize features, you change dimension values, or specify different angles or termination methods, or relationships to other features to redefine them.
When you edit an Autodesk Inventor component in an assembly, you change all occurrences of the component in its source file, and in other assemblies. To make a custom version of a component in only one assembly, save the component in a part file with a different name.
In an assembly, constraints position the components relative to one another. To fit components together easily, you can include work features while creating components. For example, place a work axis on a cylinder center. Place a hole center to align the components along their center axes of their alignment when manufactured.