Seeing progress is nice and all, but I figured showing little hints on how to mold your cardboard would be a lot more helpful for those trying it out for the first time!
Here we have the importance of inverted darts. A dart is when you pull two sides closer together to curve your structure, however sometimes you need to bend the cardboard in two different directions. Unlike foam where you can heat form it, you'll have to help it by cutting seams to break the direction of flow. Larger pieces don't always need this treatment, but anything small and/or sharp turns can't work without it. Ever try to make a sphere with cardboard? Yes.. I've tried too, then cried a little inside.
You'll naturally have gaps that need to be filled afterwards, but they are small and easy to hide. The picture above shows my starting point for the armour that sits on his hip. It needs to curve around my waist, and then curve outwards like a boot cut flair. Adding these inverted darts is already curving the top area without even applying any pressure or change to pattern. The left side is untouched, so you can see how it's still flat. Sorry if it's a little hard to tell... pictures cause images to look flat, and this was the best angle I could muster.
Unlike normal darts, inverted darts need a bit more force to separate and a placeholder to keep them apart. I use strips of cardboard underneath, and glue to hold it. Anything flimsy, like tape or fabric won't work because you're forcing the cardboard to bend in a way it's not meant to bend.
Ummm... this is my first attempt at explaining something specific. If enough people are interested, I can post more helpful tips & tricks. Of course, if people don't mind rambling explanations either, haha.