Step 1: Breastplate and Backplate

Having quite a bit of experience making clothing, I figured fitting cardboard around the body would not be too difficult. As it turns out, there are some differences between the stiff cardboard and the much more malleable fabric. I worked out a technique of scoring the back of the cardboard with the cap of a pen along lines I wanted it to bend on. This, along with a way of making darts, allowed me to shape the cardboard fairly accurately.

For the front and back plates (together these are called a cuirass), I first drew a flat shaped based on my body measurements. For the front I used these:

  • front of the waist (a little more than half my waist measurement)
  • length from waist to shoulder across bust
  • length from waist to bottom of neck hole
  • front of the bust (quite a bit more than half my bust measurement)
  • width from arm to arm, above the bust
  • length from waistline to underarm hole
For the back I used these:

  • back of the waist
  • length from waist to shoulder
  • length from waist to bottom of neck hole
  • width from underarm to underarm
  • width from arm to arm across the shoulder blades
I drew the front with darts at the bust so the armor plate would fold out there. (I didn't bother to put any darts in the back plate and this was fine.) A less busty person would need less of a dart, but most people will need at least a small one. We're all just curvier in front. I did place the waistline for each piece on the edge of an existing fold, where the original box had an edge. I also left about an inch of extra cardboard there out of habit, but it turned out this was a good thing (see Step 6 about the pauldrons).

Cut out the pieces with a knife of some kind - a utility knife or box cutter works well. Cut only the lower side of the dart marking all the way through. The upper side, cut through only the top layer of cardboard. Then peel the top layer and the corrugations off, revealing the inside of the corrugated sheet. It looks like a small flap. To construct the darts, bend the cardboard so the dart edges meet, and hot glue the flap down to the outside of the front plate.

It's easier to bend the cardboard if you score the inside first, just run the cap of a pen firmly along the line you want to bend on. A stiff ruler helps a lot for scores that run diagonally to the corrugations. In addition to the bust area, score and bend the shoulders and sides.
Ender12346 years ago
ha ha man my friends are never going to stop making fun of me when I build this...I'm going to try to put some foam camp pad down on the front and back of the "cuirass" to see if it'll hold up better (we hit pretty hard with or foam swords). I'll let you know how it goes. I atcually don't larp, but my friends and I saw Role Models were very inspired :).
yo i was able to solve the 3d problem with cardboard by bending it at close intervals to create a bent piece