This is a gizmo I created to easily create breakdowns in Nuke. It works by hooking it up to the different sections of your tree that you want to highlight and then selecting a output type.
Basically just hook up the inputs down you node tree. input-1 would be the back layer, or raw footage. Input 2 would be after the first major change then 3 and so on...
The 'Output Types' are...
Layer - which passes through whatever layer 'Output Layer' is set to.
Card Stack - which drops each input up to 'Output Layer' onto it's own card and spaces them out in 3d space. This is viewed from a camera which is by default set to around a 45 degree angle. You can animate this camera with the Camera tab.
Animated - flips though the inputs lowest to highest with controls for speed and transition type
Premult Inputs - just cuts out the alpha if the input has one generally used for 'Card Stack' mode
Differencer - differences each input with the one before it. this allows you to put an input before and after some color correction and the input after will just be exactly what those color correction nodes are adding.
Frame Hold - Locks all the inputs to the 'Hold Frame'