I guess I’d be inclined to alter the Building Block Dress skirt, but that’s just me. You’ll get a very different effect if you use box pleats, in large part because the black sections between the candy corns will be wider and won’t taper to points at the hem. Does that make sense? I think it would be easier to get the same look as the original if you started with the dress skirt pattern and determine where the points will lie at the top and bottom edges. It will take a little math, but it’s very doable. And it should look very cute! My only concern would be getting the skirt on and off. An elastic waist won’t give the same effect, so you might have to add a waistband and zipper closure.