Samurai armor is definitely the most challenging project we've attempted in a while. The helmet is nearly finished and the armor is coming along nicely.
We followed the directions on the Clan Yama Kaminari "How to make armor" page using foam core poster board covered with Duct tape instead of the plastic barrel they recommend. It's easier to cut than the plastic and he'll outgrow it too soon to make it worth going through all that. Also, he doesn't plan to go out and pound on people with sticks while wearing this. They only wear headgear and hand and foot protection when they pound on each other with sticks in his karate class.
Unlike the barrels, foam core poster board isn't flexible, so I cut part way through at 1.5 inch intervals on the side panels before applying black duct tape. This allows the armor to bend in order to fit. Instead of taking the time to lace the panels together, we used red duct tape for the hinges. We will be lacing the upper pieces to the front and back as well as the shoulder straps. Torso armor (Do) should be completed by tomorrow evening. Helmet (Kabuto) shortly afterwards. If we have time, we'll add additional pieces as we have time. Armor should be completed in time for next year's Renaissance festival (or an SCA event if we can find one nearby sooner).