There are a few tools out there that will allow you to cut a layer in After Effects for visual appeal and animation. Adding another, AeScripts + AePlugins adds a new tool to that list with Divide and Corner.
Divide a layer into layers, masks or shape layers with many options
Divide and corner will cut a layer using masks. It does this with a bunch of controllable options as well. You can either choose to divide the layer into masks on the same layer or alternatively, you can divide the layer up to several new layers. This also gives you the option to make the new layers into shape layers.
The script will also comes with some control over the corners, coming with five different corner types to choose from.
Divide and Corner will work on a composition, pre-comp, or solid level. The script is ideal to create and animated collage effect easily. Divide an Corner can be found on AeScripts + AePlugins from author Eofain PTorrez.
