The Cardboard Cutout Java Script is the backbone of how I digitally draw comics, in the Wireframes step, and is a HUGE time saver!
A Cardboard Cutout is a Layer Group containing a lineart drawing on one layer (usually this is a drawing of a figure), a contour line around that lineart on another layer, and a knockout layer under all of that (to block out the background).
Once you've drawn the lineart for your figure, the Cardboard Cutout Java Script automates everything else! It creates the Layer Group, contour line and the knockout layer!
Below is an easy to follow step-by-step YouTube tutorial, demonstrating the use of this Cardboard Cutout Java Script.
Cardboard Cutouts are also featured in my How to book:
the DC Comics Guide to Digitally Drawing Comics